src/Compilers/CSharp/Test/Syntax/LexicalAndXml/LexicalTests.cs - main - githubmirror/roslyn

src/Compilers/CSharp/Test/Syntax/LexicalAndXml/LexicalTests.cs
4 638 строк178 KB
Jason Malinowski
Switch code that was using Assert.True/False as a replacement for .Fail
21 апр 2026, 23:28
21 апр 2026, 23:283bf59ba
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

#nullable disable

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Threading;
using Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax;
using Microsoft.CodeAnalysis.CSharp.Test.Utilities;
using Microsoft.CodeAnalysis.Text;
using Roslyn.Test.Utilities;
using Xunit;
using InternalSyntax = Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax;

namespace Microsoft.CodeAnalysis.CSharp.UnitTests
{
    public class LexicalTests
    {
        private readonly CSharpParseOptions _options;
        private readonly CSharpParseOptions _options6;
        private readonly CSharpParseOptions _options7;
        private readonly CSharpParseOptions _options72;
        private readonly CSharpParseOptions _binaryOptions;
        private readonly CSharpParseOptions _underscoreOptions;
        private readonly CSharpParseOptions _binaryUnderscoreOptions;

        public LexicalTests()
        {
            _options = new CSharpParseOptions(languageVersion: LanguageVersion.CSharp3);
            _options6 = new CSharpParseOptions(languageVersion: LanguageVersion.CSharp6);
            _options7 = new CSharpParseOptions(languageVersion: LanguageVersion.CSharp7);
            _options72 = new CSharpParseOptions(languageVersion: LanguageVersion.CSharp7_2);
            _binaryOptions = _options7;
            _underscoreOptions = _options7;
            _binaryUnderscoreOptions = _binaryOptions;
        }

        private IEnumerable<SyntaxToken> Lex(string text, CSharpParseOptions options = null)
        {
            return SyntaxFactory.ParseTokens(text, options: options);
        }

        private SyntaxToken LexToken(string text, CSharpParseOptions options = null)
        {
            SyntaxToken result = default(SyntaxToken);
            foreach (var token in Lex(text, options))
            {
                if (result.Kind() == SyntaxKind.None)
                {
                    result = token;
                }
                else if (token.Kind() == SyntaxKind.EndOfFileToken)
                {
                    continue;
                }
                else
                {
                    Assert.Fail("More than one token was lexed: " + token);
                }
            }
            if (result.Kind() == SyntaxKind.None)
            {
                Assert.Fail("No tokens were lexed");
            }
            return result;
        }

        private SyntaxToken DebuggerLex(string text)
        {
            using (var lexer = new InternalSyntax.Lexer(SourceText.From(text), _options))
            {
                return new SyntaxToken(lexer.Lex(InternalSyntax.LexerMode.DebuggerSyntax));
            }
        }

        private SyntaxToken DebuggerLexToken(string text)
        {
            return DebuggerLex(text);
        }

        private IEnumerable<InternalSyntax.BlendedNode> Blend(string text)
        {
            using (var lexer = new InternalSyntax.Lexer(SourceText.From(text), _options))
            {
                var blender = new InternalSyntax.Blender(lexer, null, null);
                InternalSyntax.BlendedNode result;
                do
                {
                    result = blender.ReadToken(InternalSyntax.LexerMode.Syntax);
                    blender = result.Blender;
                    yield return result;
                }
                while (result.Token.Kind != SyntaxKind.EndOfFileToken);
            }
        }

        [Fact]
        [Trait("Feature", "Comments")]
        public void TestSingleLineComment()
        {
            var text = "// comment";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            Assert.Equal(text.Length, token.FullWidth);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            var trivia = token.LeadingTrivia.ToArray();
            Assert.Equal(1, trivia.Length);
            Assert.NotEqual(default, trivia[0]);
            Assert.Equal(SyntaxKind.SingleLineCommentTrivia, trivia[0].Kind());
        }

        [Fact]
        [Trait("Feature", "Comments")]
        public void TestSingleLineCommentWithUnicode()
        {
            var text = "// ҉ ҉̵̞̟̠̖̗̘̙̜̝̞̟̠͇̊̋̌̍̎̏̐̑̒̓̔̊̋̌̍̎̏̐̑̒̓̔̿̿̿… ͡҉҉ ̵̡̢̛̗̘̙̜̝̞̟̠͇̊̋̌̍̎̏̿̿̿̚ ҉ ҉҉̡̢̡̢̛̛̖̗̘̙̜̝̞̟̠̖̗̘̙̜̝̞̟̠̊̋̌̍̎̏̐̑̒̓̔̊̋̌… ̒̓̔̕̚ ̍̎̏̐̑̒̓̔̕̚̕̚ ̡̢̛̗̘̙̜̝̞̟̠̊̋̌̍̎̏̚ ̡̢̡̢̛̛̖̗̘̙̜̝̞̟̠̖̗̘̙̜̝̞̟̠̊̋̌̍̎̏̐̑̒̓̔̊̋̌̍̎… ̕̚̕̚ ̔̕̚̕̚҉ ҉̵̞̟̠̖̗̘̙̜̝̞̟̠͇̊̋̌̍̎̏̐̑̒̓̔̊̋̌̍̎̏̐̑̒̓̔̿̿̿… ͡҉҉ ̵̡̢̛̗̘̙̜̝̞̟̠͇̊̋̌̍̎̏̿̿̿̚ ҉ ";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            Assert.Equal(text.Length, token.FullWidth);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            var trivia = token.LeadingTrivia.ToArray();
            Assert.Equal(1, trivia.Length);
            Assert.NotEqual(default, trivia[0]);
            Assert.Equal(SyntaxKind.SingleLineCommentTrivia, trivia[0].Kind());
        }

        [Fact]
        [Trait("Feature", "Comments")]
        public void TestSingleLineXmlComment()
        {
            string text = "/// xml comment";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            Assert.Equal(text.Length, token.FullWidth);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            var trivia = token.LeadingTrivia.ToArray();
            Assert.Equal(1, trivia.Length);
            Assert.NotEqual(default, trivia[0]);
            Assert.Equal(SyntaxKind.SingleLineDocumentationCommentTrivia, trivia[0].Kind());
        }

        [WorkItem(537500, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/537500")]
        [Fact]
        [Trait("Feature", "Comments")]
        public void TestSingleLineDocCommentFollowedBySlash()
        {
            string text = "////test";
            var token = LexToken(text);

            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            Assert.False(token.ContainsDiagnostics);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);

            var trivia = token.LeadingTrivia.Single();
            Assert.Equal(SyntaxKind.SingleLineCommentTrivia, trivia.Kind());
            Assert.Equal(text, trivia.ToFullString());
            Assert.Equal(text, trivia.ToString());
            Assert.False(trivia.ContainsDiagnostics);
            Assert.Equal(0, errors.Length);
        }

        [Fact]
        [Trait("Feature", "Comments")]
        public void TestMultiLineCommentOnOneLine()
        {
            var text = "/* comment */";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            var trivia = token.GetLeadingTrivia().ToArray();
            Assert.Equal(1, trivia.Length);
            Assert.NotEqual(default, trivia[0]);
            Assert.Equal(SyntaxKind.MultiLineCommentTrivia, trivia[0].Kind());
        }

        [Fact]
        [Trait("Feature", "Comments")]
        public void TestMultiLineCommentOnMultipleLines()
        {
            var text =
@"/* 
 comment 
 on many lines
*/";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            var trivia = token.GetLeadingTrivia().ToArray();
            Assert.Equal(1, trivia.Length);
            Assert.NotEqual(default, trivia[0]);
            Assert.Equal(SyntaxKind.MultiLineCommentTrivia, trivia[0].Kind());
        }

        [Fact]
        [Trait("Feature", "Comments")]
        public void TestMultiLineXmlCommentOnMultipleLines()
        {
            var text =
@"/** 
 xml comment 
 on many lines
**/";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            var trivia = token.GetLeadingTrivia().ToArray();
            Assert.Equal(1, trivia.Length);
            Assert.NotEqual(default, trivia[0]);
            Assert.Equal(SyntaxKind.MultiLineDocumentationCommentTrivia, trivia[0].Kind());
        }

        [Fact]
        [Trait("Feature", "Comments")]
        public void TestUnterminatedMultiLineComment()
        {
            var text = "/* comment";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            var trivia = token.GetLeadingTrivia().ToArray();
            Assert.Equal(1, trivia.Length);
            Assert.NotEqual(default, trivia[0]);
            Assert.Equal(SyntaxKind.MultiLineCommentTrivia, trivia[0].Kind());
            errors = trivia[0].Errors();
            Assert.Equal(1, errors.Length);
        }

        [Fact]
        [Trait("Feature", "Comments")]
        public void TestMultiLineCommentOnOneLine_Razor()
        {
            var text = "@* comment *@";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            var errors = token.Errors();
            errors.Verify(
                // error CS1056: Unexpected character '@'
                TestBase.Diagnostic(ErrorCode.ERR_UnexpectedCharacter).WithArguments("@").WithLocation(1, 1));
            var trivia = token.GetLeadingTrivia().ToArray();
            Assert.Equal(1, trivia.Length);
            Assert.NotEqual(default, trivia[0]);
            Assert.Equal(SyntaxKind.MultiLineCommentTrivia, trivia[0].Kind());
        }

        [Fact]
        [Trait("Feature", "Comments")]
        public void TestMultiLineCommentOnMultipleLines_Razor()
        {
            var text =
@"@* 
 comment 
 on many lines
*@";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            var errors = token.Errors();
            errors.Verify(
                // error CS1056: Unexpected character '@'
                TestBase.Diagnostic(ErrorCode.ERR_UnexpectedCharacter).WithArguments("@").WithLocation(1, 1));
            var trivia = token.GetLeadingTrivia().ToArray();
            Assert.Equal(1, trivia.Length);
            Assert.NotEqual(default, trivia[0]);
            Assert.Equal(SyntaxKind.MultiLineCommentTrivia, trivia[0].Kind());
        }

        [Fact]
        [Trait("Feature", "Comments")]
        public void TestMultiLineXmlCommentOnMultipleLines_Razor()
        {
            var text =
@"@** 
 xml comment 
 on many lines
**@";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            var errors = token.Errors();
            errors.Verify(
                // error CS1056: Unexpected character '@'
                TestBase.Diagnostic(ErrorCode.ERR_UnexpectedCharacter).WithArguments("@").WithLocation(1, 1));
            var trivia = token.GetLeadingTrivia().ToArray();
            Assert.Equal(1, trivia.Length);
            Assert.NotEqual(default, trivia[0]);
            Assert.Equal(SyntaxKind.MultiLineCommentTrivia, trivia[0].Kind());
        }

        [Fact]
        [Trait("Feature", "Comments")]
        public void TestUnterminatedMultiLineComment_Razor_01()
        {
            var text = "@* comment";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            var errors = token.Errors();
            errors.Verify(
                // error CS1056: Unexpected character '@'
                TestBase.Diagnostic(ErrorCode.ERR_UnexpectedCharacter).WithArguments("@").WithLocation(1, 1),
                // error CS1035: End-of-file found, '*/' expected
                TestBase.Diagnostic(ErrorCode.ERR_OpenEndedComment).WithLocation(1, 1));
            var trivia = token.GetLeadingTrivia().ToArray();
            Assert.Equal(1, trivia.Length);
            Assert.NotEqual(default, trivia[0]);
            Assert.Equal(SyntaxKind.MultiLineCommentTrivia, trivia[0].Kind());
        }

        [Fact]
        [Trait("Feature", "Comments")]
        public void TestUnterminatedMultiLineComment_Razor_02()
        {
            var text = "@*@";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            var errors = token.Errors();
            errors.Verify(
                // error CS1056: Unexpected character '@'
                TestBase.Diagnostic(ErrorCode.ERR_UnexpectedCharacter).WithArguments("@").WithLocation(1, 1),
                // error CS1035: End-of-file found, '*/' expected
                TestBase.Diagnostic(ErrorCode.ERR_OpenEndedComment).WithLocation(1, 1));
            var trivia = token.GetLeadingTrivia().ToArray();
            Assert.Equal(1, trivia.Length);
            Assert.NotEqual(default, trivia[0]);
            Assert.Equal(SyntaxKind.MultiLineCommentTrivia, trivia[0].Kind());
        }

        [Fact]
        [Trait("Feature", "Comments")]
        public void TestUnterminatedMultiLineComment_WrongTerminator_Razor_01()
        {
            var text = "@* comment */";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            var errors = token.Errors();
            errors.Verify(
                // error CS1056: Unexpected character '@'
                TestBase.Diagnostic(ErrorCode.ERR_UnexpectedCharacter).WithArguments("@").WithLocation(1, 1),
                // error CS1035: End-of-file found, '*/' expected
                TestBase.Diagnostic(ErrorCode.ERR_OpenEndedComment).WithLocation(1, 1));
            var trivia = token.GetLeadingTrivia().ToArray();
            Assert.Equal(1, trivia.Length);
            Assert.NotEqual(default, trivia[0]);
            Assert.Equal(SyntaxKind.MultiLineCommentTrivia, trivia[0].Kind());
        }

        [Fact]
        [Trait("Feature", "Comments")]
        public void TestUnterminatedMultiLineComment_WrongTerminator_Razor_02()
        {
            var text = "/* comment *@";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            var errors = token.Errors();
            errors.Verify(
                // error CS1035: End-of-file found, '*/' expected
                TestBase.Diagnostic(ErrorCode.ERR_OpenEndedComment).WithLocation(1, 1));
            var trivia = token.GetLeadingTrivia().ToArray();
            Assert.Equal(1, trivia.Length);
            Assert.NotEqual(default, trivia[0]);
            Assert.Equal(SyntaxKind.MultiLineCommentTrivia, trivia[0].Kind());
        }

        [Theory]
        [InlineData('/', '@')]
        [InlineData('@', '/')]
        public void TestMixedMultiLineCommentTerminators_01(char outsideDelimiter, char insideDelimiter)
        {
            var text = $"{outsideDelimiter}* *{insideDelimiter} *{outsideDelimiter}";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            var errors = token.Errors();
            if (outsideDelimiter == '@')
            {
                errors.Verify(
                    // error CS1056: Unexpected character '@'
                    TestBase.Diagnostic(ErrorCode.ERR_UnexpectedCharacter).WithArguments("@").WithLocation(1, 1));
            }
            else
            {
                errors.Verify();
            }
            var trivia = token.GetLeadingTrivia().ToArray();
            Assert.Equal(1, trivia.Length);
            Assert.NotEqual(default, trivia[0]);
            Assert.Equal(SyntaxKind.MultiLineCommentTrivia, trivia[0].Kind());
        }

        [Fact]
        [Trait("Feature", "Razor")]
        public void TestAtColonTreatedAsBadRazorContentToken_RazorRecovery()
        {
            var text = "@: More text";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.RazorContentToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            var errors = token.Errors();
            errors.Verify(
                // error CS1646: Keyword, identifier, or string expected after verbatim specifier: @
                TestBase.Diagnostic(ErrorCode.ERR_ExpectedVerbatimLiteral).WithLocation(1, 1));
            Assert.Empty(token.LeadingTrivia);
            Assert.Empty(token.TrailingTrivia);
        }

        [Fact]
        [Trait("Feature", "Razor")]
        public void TestAtColonTreatedAsBadRazorContentTokenEndOfLine_RazorRecovery()
        {
            var text = """
                Identifier @: More text
                // Regular comment
                SecondIdentifier
                """;
            var tokens = Lex(text).ToList();
            var token = tokens[0];

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Empty(token.Errors());

            token = tokens[1];
            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.RazorContentToken, token.Kind());
            var errors = token.Errors();
            errors.Verify(
                // error CS1646: Keyword, identifier, or string expected after verbatim specifier: @
                TestBase.Diagnostic(ErrorCode.ERR_ExpectedVerbatimLiteral).WithLocation(1, 1));
            Assert.Empty(token.LeadingTrivia);
            Assert.Single(token.TrailingTrivia);
            Assert.Equal(SyntaxKind.EndOfLineTrivia, token.TrailingTrivia[0].Kind());
            Assert.Equal("@: More text", token.Text);

            token = tokens[2];
            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal("""
                // Regular comment
                SecondIdentifier
                """, token.ToFullString());
        }

        [Fact]
        [Trait("Feature", "Razor")]
        public void TestAtColonTreatedAsBadRazorContentToken_TrailingMultiLine_RazorRecovery()
        {
            var text = """
                @: /*
                Identifier
                */
                """;

            var tokens = Lex(text).ToList();
            var token = tokens[0];

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.RazorContentToken, token.Kind());
            Assert.Equal("@: /*", token.ToString());
            var errors = token.Errors();
            errors.Verify(
                // error CS1646: Keyword, identifier, or string expected after verbatim specifier: @
                TestBase.Diagnostic(ErrorCode.ERR_ExpectedVerbatimLiteral).WithLocation(1, 1));
            Assert.Empty(token.LeadingTrivia);
            Assert.Single(token.TrailingTrivia);
            Assert.Equal(SyntaxKind.EndOfLineTrivia, token.TrailingTrivia[0].Kind());

            token = tokens[1];
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal("Identifier", token.Text);
        }

        [Fact]
        [Trait("Feature", "Razor")]
        public void TestAtColonTreatedAsBadRazorContentToken_PreprocessorDisabled_RazorRecovery()
        {
            var text = """
                #if false
                @:
                #endif
                """;

            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            var errors = token.Errors();
            errors.Verify();
            var trivia = token.GetLeadingTrivia().ToArray();
            Assert.Equal(3, trivia.Length);
            Assert.Equal(SyntaxKind.IfDirectiveTrivia, trivia[0].Kind());
            Assert.Equal(SyntaxKind.DisabledTextTrivia, trivia[1].Kind());
            Assert.Equal(SyntaxKind.EndIfDirectiveTrivia, trivia[2].Kind());
        }

        [Fact]
        [Trait("Feature", "Razor")]
        public void TestAtColonTreatedAsBadRazorContentToken_PreprocessorEnabled_RazorRecovery()
        {
            var text = """
                #if true
                @:
                #endif
                """;

            var tokens = Lex(text).ToArray();
            Assert.Equal(2, tokens.Length);
            var token = tokens[0];

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.RazorContentToken, token.Kind());
            Assert.Equal("""
                #if true
                @:

                """, token.ToFullString());
            var errors = token.Errors();
            errors.Verify(
                // error CS1646: Keyword, identifier, or string expected after verbatim specifier: @
                TestBase.Diagnostic(ErrorCode.ERR_ExpectedVerbatimLiteral).WithLocation(1, 1));
            Assert.Single(token.GetLeadingTrivia());
            Assert.Equal(SyntaxKind.IfDirectiveTrivia, token.GetLeadingTrivia()[0].Kind());

            token = tokens[1];
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal("#endif", token.ToFullString());
            Assert.Single(token.GetLeadingTrivia());
            Assert.Equal(SyntaxKind.EndIfDirectiveTrivia, token.GetLeadingTrivia()[0].Kind());
            Assert.Empty(token.GetTrailingTrivia());
        }

        [Fact]
        [Trait("Feature", "Comments")]
        public void TestCommentWithTextWindowSentinel()
        {
            Assert.Equal('\uFFFF', SlidingTextWindow.InvalidCharacter);
            var text = "// com\uFFFFment";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            Assert.Equal(text.Length, token.FullWidth);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            var trivia = token.LeadingTrivia.ToArray();
            Assert.Equal(1, trivia.Length);
            Assert.NotEqual(default, trivia[0]);
            Assert.Equal(SyntaxKind.SingleLineCommentTrivia, trivia[0].Kind());
        }

        [Fact]
        [Trait("Feature", "Identifiers")]
        public void TestSingleLetterIdentifier()
        {
            var text = "a";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Identifiers")]
        public void TestMultiLetterIdentifier()
        {
            var text = "abc";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Identifiers")]
        public void TestMixedAlphaNumericIdentifier()
        {
            var text = "a0b1c2";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Identifiers")]
        public void TestIdentifierWithUnicode()
        {
            var text = "Fō̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄̄o";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Identifiers")]
        public void TestIdentifierWithSpaceLookingCharacters()
        {
            var text = "my͏very͏long͏identifier"; // These are COMBINING GRAPHEME JOINERs, not actual spaces
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Identifiers")]
        public void TestVerbatimSingleLetterIdentifier()
        {
            var text = "@x";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal("x", token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Identifiers")]
        public void TestVerbatimKeywordIdentifier()
        {
            var text = "@if";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal("if", token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Identifiers")]
        public void TestUnicodeEscapeIdentifier()
        {
            var text = "\\u1234";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.NotNull(token.ValueText);
            Assert.IsType<string>(token.ValueText);
            Assert.Equal(1, ((string)token.ValueText).Length);
        }

        [Fact]
        [Trait("Feature", "Identifiers")]
        public void TestVerbatimUnicodeEscapeIdentifier()
        {
            var text = "@\\u1234";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.NotNull(token.ValueText);
            Assert.IsType<string>(token.ValueText);
            Assert.Equal(1, ((string)token.ValueText).Length);
        }

        [Fact]
        [Trait("Feature", "Identifiers")]
        public void TestLongUnicodeEscapeIdentifier()
        {
            var text = "\\U00001234";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.NotNull(token.ValueText);
            Assert.IsType<string>(token.ValueText);
            Assert.Equal(1, ((string)token.ValueText).Length);
        }

        [Fact]
        [Trait("Feature", "Identifiers")]
        public void TestVerbatimLongUnicodeEscapeIdentifier()
        {
            var text = "@\\U00001234";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.NotNull(token.ValueText);
            Assert.IsType<string>(token.ValueText);
            Assert.Equal(1, ((string)token.ValueText).Length);
        }

        [Fact]
        [Trait("Feature", "Identifiers")]
        public void TestMixedUnicodeEscapeIdentifier()
        {
            var text = "a\\u1234b";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.NotNull(token.ValueText);
            Assert.IsType<string>(token.ValueText);
            Assert.Equal(3, ((string)token.ValueText).Length);
        }

        [Fact]
        [Trait("Feature", "Identifiers")]
        public void TestMultiUnicodeEscapeIdentifier()
        {
            var text = "a\\u1234\\u5678b";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.NotNull(token.ValueText);
            Assert.IsType<string>(token.ValueText);
            Assert.Equal(4, ((string)token.ValueText).Length);
        }

        [Fact]
        [Trait("Feature", "Identifiers")]
        public void TestBadUnicodeEscapeIdentifier()
        {
            var text = "\\u123";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(text, token.ToFullString());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.NotNull(token.ValueText);
            Assert.IsType<string>(token.ValueText);
            Assert.Equal(1, ((string)token.ValueText).Length);
        }

        [Fact]
        [Trait("Feature", "Identifiers")]
        public void TestAllVerbatimKeywordsAsIdentifiers()
        {
            foreach (var keyword in SyntaxFacts.GetKeywordKinds())
            {
                if (SyntaxFacts.IsReservedKeyword(keyword))
                {
                    var value = SyntaxFacts.GetText(keyword);
                    var text = "@" + value;
                    var token = LexToken(text);

                    Assert.NotEqual(default, token);
                    Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
                    Assert.Equal(text, token.Text);
                    var errors = token.Errors();
                    Assert.Equal(0, errors.Length);
                    Assert.Equal(value, token.ValueText);
                }
            }
        }

        [Fact]
        [Trait("Feature", "Identifiers")]
        public void TestNonLatinIdentifier()
        {
            var text = "\u00C6sh";
            var token = LexToken(text);

            Assert.NotEqual('\\', text[0]);
            Assert.Equal(System.Globalization.UnicodeCategory.UppercaseLetter, CharUnicodeInfo.GetUnicodeCategory(text[0]));

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.NotNull(token.ValueText);
            Assert.IsType<string>(token.ValueText);
            Assert.Equal(3, ((string)token.ValueText).Length);
        }

        [Fact]
        [Trait("Feature", "Keywords")]
        public void TestAllLanguageKeywords()
        {
            foreach (var keyword in SyntaxFacts.GetKeywordKinds())
            {
                if (SyntaxFacts.IsReservedKeyword(keyword))
                {
                    var text = SyntaxFacts.GetText(keyword);
                    var token = LexToken(text);

                    Assert.NotEqual(default, token);
                    Assert.True(SyntaxFacts.IsReservedKeyword(token.Kind()));
                    Assert.Equal(text, token.Text);
                    var errors = token.Errors();
                    Assert.Equal(0, errors.Length);
                    Assert.Equal(text, token.ValueText);
                }
            }
        }

        [Fact]
        [Trait("Feature", "Punctuation")]
        public void TestAllLanguagePunctuation()
        {
            TestPunctuation(SyntaxKind.TildeToken);
            TestPunctuation(SyntaxKind.ExclamationToken);

            // TestPunctuation(ParseKind.Dollar);    debugger only
            TestPunctuation(SyntaxKind.PercentToken);
            TestPunctuation(SyntaxKind.CaretToken);
            TestPunctuation(SyntaxKind.AmpersandToken);
            TestPunctuation(SyntaxKind.AsteriskToken);
            TestPunctuation(SyntaxKind.OpenParenToken);
            TestPunctuation(SyntaxKind.CloseParenToken);
            TestPunctuation(SyntaxKind.MinusToken);
            TestPunctuation(SyntaxKind.PlusToken);
            TestPunctuation(SyntaxKind.EqualsToken);
            TestPunctuation(SyntaxKind.OpenBraceToken);
            TestPunctuation(SyntaxKind.CloseBraceToken);
            TestPunctuation(SyntaxKind.OpenBracketToken);
            TestPunctuation(SyntaxKind.CloseBracketToken);
            TestPunctuation(SyntaxKind.BarToken);

            // TestPunctuation(ParseKind.BackSlash);   escape
            TestPunctuation(SyntaxKind.ColonToken);
            TestPunctuation(SyntaxKind.SemicolonToken);

            // TestPunctuation(ParseKind.DoubleQuote);   string literal
            // TestPunctuation(ParseKind.Quote);         character literal
            TestPunctuation(SyntaxKind.LessThanToken);
            TestPunctuation(SyntaxKind.CommaToken);
            TestPunctuation(SyntaxKind.GreaterThanToken);
            TestPunctuation(SyntaxKind.DotToken);
            TestPunctuation(SyntaxKind.QuestionToken);

            // TestPunctuation(ParseKind.Hash);  preprocessor only
            TestPunctuation(SyntaxKind.SlashToken);
            TestPunctuation(SyntaxKind.BarBarToken);
            TestPunctuation(SyntaxKind.AmpersandAmpersandToken);
            TestPunctuation(SyntaxKind.MinusMinusToken);
            TestPunctuation(SyntaxKind.PlusPlusToken);
            TestPunctuation(SyntaxKind.ColonColonToken);
            TestPunctuation(SyntaxKind.QuestionQuestionToken);
            TestPunctuation(SyntaxKind.MinusGreaterThanToken);
            TestPunctuation(SyntaxKind.ExclamationEqualsToken);
            TestPunctuation(SyntaxKind.EqualsEqualsToken);
            TestPunctuation(SyntaxKind.EqualsGreaterThanToken);
            TestPunctuation(SyntaxKind.LessThanEqualsToken);
            TestPunctuation(SyntaxKind.LessThanLessThanToken);
            TestPunctuation(SyntaxKind.LessThanLessThanEqualsToken);
            TestPunctuation(SyntaxKind.GreaterThanEqualsToken);

            // TestPunctuation(ParseKind.GreaterThanGreaterThan);  not directly lexed  (generics)
            // TestPunctuation(ParseKind.GreaterThanGreaterThanEquals);  not directly lexed (generics)
            TestPunctuation(SyntaxKind.SlashEqualsToken);
            TestPunctuation(SyntaxKind.AsteriskEqualsToken);
            TestPunctuation(SyntaxKind.BarEqualsToken);
            TestPunctuation(SyntaxKind.AmpersandEqualsToken);
            TestPunctuation(SyntaxKind.PlusEqualsToken);
            TestPunctuation(SyntaxKind.MinusEqualsToken);
            TestPunctuation(SyntaxKind.CaretEqualsToken);
            TestPunctuation(SyntaxKind.PercentEqualsToken);
            TestPunctuation(SyntaxKind.QuestionQuestionEqualsToken);
        }

        private void TestPunctuation(SyntaxKind kind)
        {
            var text = SyntaxFacts.GetText(kind);
            var token = LexToken(text);
            Assert.NotEqual(default, token);
            Assert.Equal(kind, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestStringLiteral()
        {
            var text = "\"literal\"";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.StringLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal("literal", token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestStringLiteralWithUnicode()
        {
            var text = "\"҉ ҉̵̞̟̠̖̗̘̙̜̝̞̟̠͇̊̋̌̍̎̏̐̑̒̓̔̊̋̌̍̎̏̐̑̒̓̔̿̿̿… ͡҉҉ ̵̡̢̛̗̘̙̜̝̞̟̠͇̊̋̌̍̎̏̿̿̿̚ ҉ ҉҉̡̢̡̢̛̛̖̗̘̙̜̝̞̟̠̖̗̘̙̜̝̞̟̠̊̋̌̍̎̏̐̑̒̓̔̊̋̌… ̒̓̔̕̚ ̍̎̏̐̑̒̓̔̕̚̕̚ ̡̢̛̗̘̙̜̝̞̟̠̊̋̌̍̎̏̚ ̡̢̡̢̛̛̖̗̘̙̜̝̞̟̠̖̗̘̙̜̝̞̟̠̊̋̌̍̎̏̐̑̒̓̔̊̋̌̍̎… ̕̚̕̚ ̔̕̚̕̚҉ ҉̵̞̟̠̖̗̘̙̜̝̞̟̠͇̊̋̌̍̎̏̐̑̒̓̔̊̋̌̍̎̏̐̑̒̓̔̿̿̿… ͡҉҉ ̵̡̢̛̗̘̙̜̝̞̟̠͇̊̋̌̍̎̏̿̿̿̚ ҉\"";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.StringLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal("҉ ҉̵̞̟̠̖̗̘̙̜̝̞̟̠͇̊̋̌̍̎̏̐̑̒̓̔̊̋̌̍̎̏̐̑̒̓̔̿̿̿… ͡҉҉ ̵̡̢̛̗̘̙̜̝̞̟̠͇̊̋̌̍̎̏̿̿̿̚ ҉ ҉҉̡̢̡̢̛̛̖̗̘̙̜̝̞̟̠̖̗̘̙̜̝̞̟̠̊̋̌̍̎̏̐̑̒̓̔̊̋̌… ̒̓̔̕̚ ̍̎̏̐̑̒̓̔̕̚̕̚ ̡̢̛̗̘̙̜̝̞̟̠̊̋̌̍̎̏̚ ̡̢̡̢̛̛̖̗̘̙̜̝̞̟̠̖̗̘̙̜̝̞̟̠̊̋̌̍̎̏̐̑̒̓̔̊̋̌̍̎… ̕̚̕̚ ̔̕̚̕̚҉ ҉̵̞̟̠̖̗̘̙̜̝̞̟̠͇̊̋̌̍̎̏̐̑̒̓̔̊̋̌̍̎̏̐̑̒̓̔̿̿̿… ͡҉҉ ̵̡̢̛̗̘̙̜̝̞̟̠͇̊̋̌̍̎̏̿̿̿̚ ҉", token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestVerbatimStringLiteral()
        {
            var text = "@\"literal\"";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.StringLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal("literal", token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestMultiLineVerbatimStringLiteral()
        {
            var text = "@\"multi line\r\nliteral\"";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.StringLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal("multi line\r\nliteral", token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestStringLiteralWithNewLine()
        {
            var text = "\"literal\r\nwith new line\"";
            var token = Lex(text).First();

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.StringLiteralToken, token.Kind());
            Assert.NotEqual(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_NewlineInConst, errors[0].Code);
            Assert.Equal("literal", token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestUnterminatedStringLiteral()
        {
            var text = "\"literal";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.StringLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_NewlineInConst, errors[0].Code);
            Assert.Equal("literal", token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestUnterminatedVerbatimStringLiteral()
        {
            var text = "@\"literal";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.StringLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_UnterminatedStringLit, errors[0].Code);
            Assert.Equal("literal", token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestStringLiteralWithUnicodeEscape()
        {
            var text = "\"\\u1234\"";
            var value = "\u1234";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.StringLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestStringLiteralWithLongUnicodeEscape()
        {
            var text = "\"\\U00001234\"";
            var value = "\U00001234";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.StringLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestStringLiteralWithMultipleUnicodeEscapes()
        {
            var text = "\"\\u1234\\u1234\"";
            var value = "\u1234\u1234";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.StringLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestStringLiteralWithBadUnicodeEscape()
        {
            var value = "\u0012";
            var text = "\"\\u12\"";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.StringLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_IllegalEscape, errors[0].Code);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestStringLiteralWithEscape_CSharp12()
        {
            var text = """
                "\e"
                """;
            var value = "\u001b";
            var token = LexToken(text, TestOptions.Regular12);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.StringLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            AssertEx.EqualOrDiff("error CS9202: Feature 'string escape character' is not available in C# 12.0. Please use language version 13.0 or greater.", errors[0].ToString(EnsureEnglishUICulture.PreferredOrNull));
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestStringLiteralWithEscape_Preview()
        {
            var text = """
                "\e"
                """;
            var value = "\u001b";
            var token = LexToken(text, TestOptions.Regular13);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.StringLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestVerbatimStringLiteralWithEscape()
        {
            var text = """
                @"\e"
                """;
            var value = @"\e";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.StringLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteral()
        {
            var value = "x";
            var text = "'" + value + "'";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralEscape_R()
        {
            var value = "\r";
            var text = "'\\r'";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralEscape_N()
        {
            var value = "\n";
            var text = "'\\n'";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralEscape_0()
        {
            var value = "\0";
            var text = "'\\0'";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralEscape_T()
        {
            var value = "\t";
            var text = "'\\t'";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralEscape_A()
        {
            var value = "\a";
            var text = "'\\a'";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralEscape_B()
        {
            var value = "\b";
            var text = "'\\b'";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralEscape_V()
        {
            var value = "\v";
            var text = "'\\v'";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralEscape_E_CSharp12()
        {
            var value = "\u001b";
            var text = "'\\e'";
            var token = LexToken(text, TestOptions.Regular12);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            AssertEx.EqualOrDiff("error CS9202: Feature 'string escape character' is not available in C# 12.0. Please use language version 13.0 or greater.", errors[0].ToString(EnsureEnglishUICulture.PreferredOrNull));
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralEscape_E_CSharpPreview()
        {
            var value = "\u001b";
            var text = "'\\e'";
            var token = LexToken(text, TestOptions.Regular13);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralEscape_F()
        {
            var value = "\f";
            var text = "'\\f'";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralBadEscape()
        {
            var value = "q";
            var text = "'\\q'";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralEscape_BackSlash()
        {
            var value = "\\";
            var text = "'\\\\'";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralEscape_SingleQuote()
        {
            var value = "'";
            var text = "'\\''";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralEscape_DoubleQuote()
        {
            var value = "\"";
            var text = "'\\\"'";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralUnicodeEscape()
        {
            var value = "\u1234";
            var text = "'\\u1234'";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralLongUnicodeEscape()
        {
            var value = "\U00001234";
            var text = "'\\U00001234'";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralWithBadUnicodeEscape()
        {
            var value = "\u0012";
            var text = "'\\u12'";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_IllegalEscape, errors[0].Code);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralThatsTooSmall()
        {
            var text = "''";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_EmptyCharConst, errors[0].Code);
            Assert.Equal(SlidingTextWindow.InvalidCharacter, Char.Parse(token.ValueText));
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralThatsTooBig()
        {
            var value = "a";
            var text = "'ab'";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal(text, token.Text);
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_TooManyCharsInConst, errors[0].Code);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralWithNewline()
        {
            var value = "a";
            var text = "'a\r'";
            var token = Lex(text).First();

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal("'a", token.Text);
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_NewlineInConst, errors[0].Code);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralThatsTooSmallWithNewline()
        {
            var text = "'\r'";
            var token = Lex(text).First();

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal("'", token.Text);
            var errors = token.Errors();
            Assert.Equal(2, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_NewlineInConst, errors[0].Code);
            Assert.Equal((int)ErrorCode.ERR_EmptyCharConst, errors[1].Code);
            Assert.Equal(SlidingTextWindow.InvalidCharacter, Char.Parse(token.ValueText));
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralThatsTooBigWithNewline()
        {
            var value = "a";
            var text = "'ab\r'";
            var token = Lex(text).First();

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal("'ab", token.Text);
            var errors = token.Errors();
            Assert.Equal(2, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_NewlineInConst, errors[0].Code);
            Assert.Equal((int)ErrorCode.ERR_TooManyCharsInConst, errors[1].Code);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestCharacterLiteralContainingTextWindowSentinel()
        {
            Assert.Equal('\uFFFF', SlidingTextWindow.InvalidCharacter);

            var value = "\uFFFF";
            var text = "'\uFFFF'";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.CharacterLiteralToken, token.Kind());
            Assert.Equal("'\uFFFF'", token.Text);
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(value, token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestUnicodeEscapeWithNoDigits()
        {
            var text = "\\";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.BadToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_UnexpectedCharacter, errors[0].Code);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestVerbatimIdentifierWithNoCharacters()
        {
            var text = "@";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.BadToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_ExpectedVerbatimLiteral, errors[0].Code);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestVerbatimIdentifierWithNoCharacters2()
        {
            var text = "@@";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.BadToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_ExpectedVerbatimLiteral, errors[0].Code);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestVerbatimIdentifierWithNoCharacters3()
        {
            var text = "@@@";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.BadToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_ExpectedVerbatimLiteral, errors[0].Code);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestVerbatimIdentifierWithNoCharactersAndTrivia1()
        {
            var text = "@  ";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.BadToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_ExpectedVerbatimLiteral, errors[0].Code);
            Assert.Equal(text, token.ToFullString());
            var trivia = token.GetTrailingTrivia().ToList();
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestVerbatimIdentifierWithNoCharactersAndTrivia2()
        {
            var text = "@@  ";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.BadToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_ExpectedVerbatimLiteral, errors[0].Code);
            Assert.Equal(text, token.ToFullString());
            var trivia = token.GetTrailingTrivia().ToList();
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestVerbatimIdentifierWithNoCharactersAndTrivia3()
        {
            var text = "@@@  ";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.BadToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_ExpectedVerbatimLiteral, errors[0].Code);
            Assert.Equal(text, token.ToFullString());
            var trivia = token.GetTrailingTrivia().ToList();
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestVerbatimIdentifierWithMultipleAtSign1()
        {
            var text = "@@class";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal(ErrorCode.ERR_IllegalAtSequence, (ErrorCode)errors[0].Code);
            Assert.Equal(text, token.Text);
            Assert.Equal("class", token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestVerbatimIdentifierWithMultipleAtSign2()
        {
            var text = "@@@class";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal(ErrorCode.ERR_IllegalAtSequence, (ErrorCode)errors[0].Code);
            Assert.Equal(text, token.Text);
            Assert.Equal("class", token.ValueText);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteral()
        {
            var value = 123;
            var text = "123";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithDecimal()
        {
            var value = 123.456;
            var text = "123.456";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithHugeDecimal()
        {
            var value = 123.45632434234234234234234234324234234234;
            var text = "123.45632434234234234234234234324234234234";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithHugeNumberAndDecimal()
        {
            var value = 12332434234234234234234234324234234234.456;
            var text = "12332434234234234234234234324234234234.456";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithHugeNumberAndHugeDecimal()
        {
            var value = 12332434234234234234234234324234234234.45623423423423423423423423423423423423;
            var text = "12332434234234234234234234324234234234.45623423423423423423423423423423423423";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithDecimalAndExponent()
        {
            var text = "123.456e10";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithDecimalAndHugeExponent()
        {
            var text = "123.456e999";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_FloatOverflow, errors[0].Code);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithDecimalAndHugeExponentAndFloatSpecifier()
        {
            var text = "123.456e999f";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_FloatOverflow, errors[0].Code);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithDecimalAndHugeExponentAndDoubleSpecifier()
        {
            var text = "123.456e999d";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_FloatOverflow, errors[0].Code);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithDecimalAndHugeExponentAndDecimalSpecifier()
        {
            var text = "123.456e999m";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_FloatOverflow, errors[0].Code);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithHugeDecimalAndDecimalSpecifier()
        {
            var text = "10234230492340923423423423423423423434234.23402349234098230498234m";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_FloatOverflow, errors[0].Code);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithExponentAndDecimalSpecifier01()
        {
            var text = "0.0E1000M";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            decimal d;
            if (decimal.TryParse("0E1", System.Globalization.NumberStyles.AllowExponent, null, out d))
            {
                Assert.Equal(0, errors.Length);
            }
            else
            {
                Assert.Equal(1, errors.Length);
                Assert.Equal((int)ErrorCode.ERR_FloatOverflow, errors[0].Code);
                Assert.Equal(text, token.Text);
            }
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithExponentAndDecimalSpecifier02()
        {
            var text = "1.0E29M";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_FloatOverflow, errors[0].Code);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithExponentAndDecimalSpecifier03()
        {
            var text = "0.1E29M";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
        }

        [WorkItem(547238, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/547238")]
        [Fact, WorkItem(547238, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/547238")]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithExponentAndDecimalSpecifier04()
        {
            var text = "0.1EM";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_InvalidReal, errors[0].Code);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithDecimalAndUpperExponent()
        {
            var text = "123.456E10";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralStartsWithDecimal()
        {
            var value = .456;
            var text = ".456";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralStartsWithDecimalAndExponent()
        {
            var value = .456e10;
            var text = ".456e10";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithFloatSpecifier()
        {
            var value = 123f;
            var text = "123f";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithUpperFloatSpecifier()
        {
            var value = 123F;
            var text = "123F";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithDecimalAndFloatSpecifier()
        {
            var value = 123.456f;
            var text = "123.456f";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithDecimalAndExponentAndFloatSpecifier()
        {
            var value = 123.456e10f;
            var text = "123.456e10f";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithDoubleSpecifier()
        {
            var value = 123d;
            var text = "123d";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithUpperDoubleSpecifier()
        {
            var value = 123D;
            var text = "123D";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithDecimalAndDoubleSpecifier()
        {
            var value = 123.456d;
            var text = "123.456d";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithDecimalAndExponentAndDoubleSpecifier()
        {
            var value = 123.456e10d;
            var text = "123.456e10D";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithDecimalSpecifier()
        {
            var value = 123m;
            var text = "123m";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithDecimalPointAndDecimalSpecifier()
        {
            var value = 123.456m;
            var text = "123.456m";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithDecimalPointAndExponentAndDecimalSpecifier()
        {
            var value = 123.456e2m;
            var text = "123.456e2m";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithUnsignedSpecifier()
        {
            var value = 123u;
            var text = "123u";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithUpperUnsignedSpecifier()
        {
            var value = 123U;
            var text = "123U";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithLongSpecifier()
        {
            var value = 123L;
            var text = "123l";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.ErrorsAndWarnings();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithUpperLongSpecifier()
        {
            var value = 123L;
            var text = "123L";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithUnsignedAndLongSpecifier()
        {
            var value = 123ul;
            var text = "123ul";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);

            text = "123lu";
            token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithUpperUnsignedAndLongSpecifier()
        {
            var value = 123Ul;
            var text = "123Ul";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);

            text = "123lU";
            token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithUnsignedAndUpperLongSpecifier()
        {
            var value = 123uL;
            var text = "123uL";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);

            text = "123Lu";
            token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralWithUpperUnsignedAndUpperLongSpecifier()
        {
            var value = 123UL;
            var text = "123UL";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);

            text = "123LU";
            token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericHexLiteralWithUnsignedAndLongSpecifier()
        {
            var value = 0x123ul;
            var text = "0x123ul";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);

            text = "0x123lu";
            token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericHexLiteralWithUpperUnsignedAndLongSpecifier()
        {
            var value = 0x123Ul;
            var text = "0x123Ul";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);

            text = "0x123lU";
            token = LexToken(text);
            errors = token.Errors();
            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericHexLiteralWithUnsignedAndUpperLongSpecifier()
        {
            var value = 0x123uL;
            var text = "0x123uL";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);

            text = "0x123Lu";
            token = LexToken(text);
            errors = token.Errors();

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericHexLiteralWithUpperUnsignedAndUpperLongSpecifier()
        {
            var value = 0x123UL;
            var text = "0x123UL";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);

            text = "0x123LU";
            token = LexToken(text);
            errors = token.Errors();

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericBinaryLiteralWithoutFeatureFlag()
        {
            var text = "0b1";
            var token = LexToken(text, _options6);

            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_FeatureNotAvailableInVersion6, errors[0].Code);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericBinaryLiteralWithUnsignedAndLongSpecifier()
        {
            var value = 0x123ul;
            var text = "0b100100011ul";
            var token = LexToken(text, _binaryOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);

            text = "0b100100011lu";
            token = LexToken(text, _binaryOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericBinaryLiteralWithUpperUnsignedAndLongSpecifier()
        {
            var value = 0x123Ul;
            var text = "0b100100011Ul";
            var token = LexToken(text, _binaryOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);

            text = "0b100100011lU";
            token = LexToken(text, _binaryOptions);
            errors = token.Errors();
            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericBinaryLiteralWithUnsignedAndUpperLongSpecifier()
        {
            var value = 0x123uL;
            var text = "0b100100011uL";
            var token = LexToken(text, _binaryOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);

            text = "0b100100011Lu";
            token = LexToken(text, _binaryOptions);
            errors = token.Errors();

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericBinaryLiteralWithUpperUnsignedAndUpperLongSpecifier()
        {
            var value = 0x123UL;
            var text = "0b100100011UL";
            var token = LexToken(text, _binaryOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);

            text = "0b100100011LU";
            token = LexToken(text, _binaryOptions);
            errors = token.Errors();

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralMaxInt32()
        {
            var text = Int32.MaxValue.ToString();
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(Int32.MaxValue, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralMaxUInt32()
        {
            var text = UInt32.MaxValue.ToString() + "U";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(UInt32.MaxValue, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralTooBigForInt32BecomesUInt32()
        {
            var value = ((uint)Int32.MaxValue) + 1;
            var text = value.ToString();
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralTooBigForUInt32BecomesInt64()
        {
            var value = ((long)UInt32.MaxValue) + 1;
            var text = value.ToString();
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralTooBigForInt64BecomesUInt64()
        {
            var value = ((ulong)Int64.MaxValue) + 1;
            var text = value.ToString();
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralTooBigForUInt32OrUInt64()
        {
            var text = UInt64.MaxValue.ToString() + "0U";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_IntOverflow, errors[0].Code);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralMaxInt64()
        {
            var text = Int64.MaxValue.ToString() + "L";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(Int64.MaxValue, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralTooBigForInt64()
        {
            var text = (((ulong)Int64.MaxValue) + 1).ToString() + "L";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal((ulong)Int64.MaxValue + 1, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralMaxUInt64()
        {
            var text = UInt64.MaxValue.ToString() + "UL";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(UInt64.MaxValue, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericLiteralTooBigForUInt64()
        {
            var text = UInt64.MaxValue.ToString() + "0UL";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_IntOverflow, errors[0].Code);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericHexLiteral()
        {
            var value = 0x123;
            var text = "0x123";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericHexLiteralWithUnsignedSpecifier()
        {
            var value = 0x123u;
            var text = "0x123u";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericHexLiteralWithLongSpecifier()
        {
            var value = 0x123L;
            var text = "0x123L";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumeric8DigitHexLiteral()
        {
            var value = 0x12345678;
            var text = "0x12345678";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumeric8DigitMaxHexLiteral()
        {
            var value = 0x7FFFFFFF;
            var text = "0x7FFFFFFF";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumeric8DigitMaxUnsignedHexLiteral()
        {
            var value = 0xFFFFFFFF;
            var text = "0xFFFFFFFF";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumeric8DigitMaxUnsignedHexLiteralWithUnsignedSpecifier()
        {
            var value = 0xFFFFFFFFu;
            var text = "0xFFFFFFFFu";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumeric16DigitMaxHexLiteral()
        {
            var value = 0x7FFFFFFFFFFFFFFF;
            var text = "0x7FFFFFFFFFFFFFFF";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumeric16DigitMaxUnsignedHexLiteral()
        {
            var value = 0xFFFFFFFFFFFFFFFF;
            var text = "0xFFFFFFFFFFFFFFFF";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericBinaryLiteral()
        {
            var value = 0x123;
            var text = "0b100100011";
            var token = LexToken(text, _binaryOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericBinaryLiteralWithUnsignedSpecifier()
        {
            var value = 0x123u;
            var text = "0b100100011u";
            var token = LexToken(text, _binaryOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericBinaryLiteralWithLongSpecifier()
        {
            var value = 0x123L;
            var text = "0b100100011L";
            var token = LexToken(text, _binaryOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumeric8DigitBinaryLiteral()
        {
            var value = 0xAA;
            var text = "0b10101010";
            var token = LexToken(text, _binaryOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumeric8DigitMaxBinaryLiteral()
        {
            var value = 0x7FFFFFFF;
            var text = "0b1111111111111111111111111111111";
            var token = LexToken(text, _binaryOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumeric8DigitMaxUnsignedBinaryLiteral()
        {
            var value = 0xFFFFFFFF;
            var text = "0b11111111111111111111111111111111";
            var token = LexToken(text, _binaryOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumeric8DigitMaxUnsignedBinaryLiteralWithUnsignedSpecifier()
        {
            var value = 0xFFFFFFFFu;
            var text = "0b11111111111111111111111111111111u";
            var token = LexToken(text, _binaryOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumeric16DigitMaxBinaryLiteral()
        {
            var value = 0x7FFFFFFFFFFFFFFF;
            var text = "0b111111111111111111111111111111111111111111111111111111111111111";
            var token = LexToken(text, _binaryOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumeric16DigitMaxUnsignedBinaryLiteral()
        {
            var value = 0xFFFFFFFFFFFFFFFF;
            var text = "0b1111111111111111111111111111111111111111111111111111111111111111";
            var token = LexToken(text, _binaryOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericOverflowBinaryLiteral()
        {
            var text = "0b10000000000000000000000000000000000000000000000000000000000000000";
            var token = LexToken(text, _binaryOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_IntOverflow, errors[0].Code);
            Assert.Equal("error CS1021: Integral constant is too large", errors[0].ToString(EnsureEnglishUICulture.PreferredOrNull));
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericEmptyBinaryLiteral()
        {
            var text = "0b";
            var token = LexToken(text, _binaryOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_InvalidNumber, errors[0].Code);
            Assert.Equal("error CS1013: Invalid number", errors[0].ToString(EnsureEnglishUICulture.PreferredOrNull));
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericWithUnderscores()
        {
            var text = "1_000";
            var token = LexToken(text, _underscoreOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(0, token.Errors().Length);
            Assert.Equal(1000, token.Value);
            Assert.Equal(text, token.Text);

            text = "1___0_0___0";
            token = LexToken(text, _underscoreOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(0, token.Errors().Length);
            Assert.Equal(1000, token.Value);
            Assert.Equal(text, token.Text);

            text = "1_000.000_1";
            token = LexToken(text, _underscoreOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(0, token.Errors().Length);
            Assert.Equal(1000.0001, token.Value);
            Assert.Equal(text, token.Text);

            text = "1_01__0.0__10_1f";
            token = LexToken(text, _underscoreOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(0, token.Errors().Length);
            Assert.Equal(1010.0101f, token.Value);
            Assert.Equal(text, token.Text);

            text = "1_01__0.0__10_1e0_1";
            token = LexToken(text, _underscoreOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(0, token.Errors().Length);
            Assert.Equal(1010.0101e01, token.Value);
            Assert.Equal(text, token.Text);

            text = "0xA_A";
            token = LexToken(text, _underscoreOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(0, token.Errors().Length);
            Assert.Equal(0xAA, token.Value);
            Assert.Equal(text, token.Text);

            text = "0b1_1";
            token = LexToken(text, _binaryUnderscoreOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(0, token.Errors().Length);
            Assert.Equal(3, token.Value);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericWithUnderscoresWithoutFeatureFlag()
        {
            var text = "1_000";
            var token = LexToken(text, _options6);

            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_FeatureNotAvailableInVersion6, errors[0].Code);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericWithLeadingUnderscores()
        {
            var text = "0x_A";
            var token = LexToken(text, _options72);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(0, token.Errors().Length);
            Assert.Equal(0xA, token.Value);
            Assert.Equal(text, token.Text);

            text = "0b_1";
            token = LexToken(text, _options72);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(0, token.Errors().Length);
            Assert.Equal(1, token.Value);
            Assert.Equal(text, token.Text);

            text = "0x__A_1L";
            token = LexToken(text, _options72);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(0, token.Errors().Length);
            Assert.Equal(0xA1L, token.Value);
            Assert.Equal(text, token.Text);

            text = "0b__1_1L";
            token = LexToken(text, _options72);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(0, token.Errors().Length);
            Assert.Equal(0b11L, token.Value);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericWithLeadingUnderscoresWithoutFeatureFlag()
        {
            var text = "0x_A";
            var token = LexToken(text, _options7);

            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_FeatureNotAvailableInVersion7, errors[0].Code);
            Assert.Equal(text, token.Text);

            text = "0b_1";
            token = LexToken(text, _options7);

            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_FeatureNotAvailableInVersion7, errors[0].Code);
            Assert.Equal(text, token.Text);

            text = "0x_1";
            token = LexToken(text, _options6);

            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_FeatureNotAvailableInVersion6, errors[0].Code);
            Assert.Equal(text, token.Text);

            text = "0x_123_456_789_ABC_DEF_123";
            token = LexToken(text, _options6);

            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(2, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_FeatureNotAvailableInVersion6, errors[0].Code);
            Assert.Equal((int)ErrorCode.ERR_IntOverflow, errors[1].Code);
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericWithBadUnderscores()
        {
            var text = "_1000";
            var token = LexToken(text, _underscoreOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(0, token.Errors().Length);

            text = "1000_";
            token = LexToken(text, _underscoreOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_InvalidNumber, errors[0].Code);
            Assert.Equal("error CS1013: Invalid number", errors[0].ToString(EnsureEnglishUICulture.PreferredOrNull));
            Assert.Equal(text, token.Text);

            text = "1000_.0";
            token = LexToken(text, _underscoreOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_InvalidNumber, errors[0].Code);
            Assert.Equal("error CS1013: Invalid number", errors[0].ToString(EnsureEnglishUICulture.PreferredOrNull));
            Assert.Equal(text, token.Text);

            // parses as Int32.Member, where Member is _0
            // TODO: Check for that it does parse as a field access
            // text = "1000._0";

            text = "1000.0_";
            token = LexToken(text, _underscoreOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_InvalidNumber, errors[0].Code);
            Assert.Equal("error CS1013: Invalid number", errors[0].ToString(EnsureEnglishUICulture.PreferredOrNull));
            Assert.Equal(text, token.Text);

            text = "1000.0_e1";
            token = LexToken(text, _underscoreOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_InvalidNumber, errors[0].Code);
            Assert.Equal("error CS1013: Invalid number", errors[0].ToString(EnsureEnglishUICulture.PreferredOrNull));
            Assert.Equal(text, token.Text);

            text = "1000.0e_1";
            token = LexToken(text, _underscoreOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_InvalidNumber, errors[0].Code);
            Assert.Equal("error CS1013: Invalid number", errors[0].ToString(EnsureEnglishUICulture.PreferredOrNull));
            Assert.Equal(text, token.Text);

            text = "1000.0e1_";
            token = LexToken(text, _underscoreOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_InvalidNumber, errors[0].Code);
            Assert.Equal("error CS1013: Invalid number", errors[0].ToString(EnsureEnglishUICulture.PreferredOrNull));
            Assert.Equal(text, token.Text);

            text = "0xA_";
            token = LexToken(text, _underscoreOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_InvalidNumber, errors[0].Code);
            Assert.Equal("error CS1013: Invalid number", errors[0].ToString(EnsureEnglishUICulture.PreferredOrNull));
            Assert.Equal(text, token.Text);

            text = "0b1_";
            token = LexToken(text, _binaryUnderscoreOptions);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_InvalidNumber, errors[0].Code);
            Assert.Equal("error CS1013: Invalid number", errors[0].ToString(EnsureEnglishUICulture.PreferredOrNull));
            Assert.Equal(text, token.Text);

            text = "0x_";
            token = LexToken(text, _options72);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_InvalidNumber, errors[0].Code);
            Assert.Equal("error CS1013: Invalid number", errors[0].ToString(EnsureEnglishUICulture.PreferredOrNull));
            Assert.Equal(text, token.Text);

            text = "0x_2_";
            token = LexToken(text, _options72);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_InvalidNumber, errors[0].Code);
            Assert.Equal("error CS1013: Invalid number", errors[0].ToString(EnsureEnglishUICulture.PreferredOrNull));
            Assert.Equal(text, token.Text);

            text = "1E+_2";
            token = LexToken(text, _options72);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_InvalidNumber, errors[0].Code);
            Assert.Equal("error CS1013: Invalid number", errors[0].ToString(EnsureEnglishUICulture.PreferredOrNull));
            Assert.Equal(text, token.Text);

            text = "1E-_2";
            token = LexToken(text, _options72);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_InvalidNumber, errors[0].Code);
            Assert.Equal("error CS1013: Invalid number", errors[0].ToString(EnsureEnglishUICulture.PreferredOrNull));
            Assert.Equal(text, token.Text);

            text = "1E_";
            token = LexToken(text, _options72);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            errors = token.Errors();
            Assert.Equal(2, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_InvalidNumber, errors[0].Code);
            Assert.Equal((int)ErrorCode.ERR_FloatOverflow, errors[1].Code);
            Assert.Equal("error CS1013: Invalid number", errors[0].ToString(EnsureEnglishUICulture.PreferredOrNull));
            Assert.Equal(text, token.Text);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericWithTrailingDot()
        {
            var value = 3;
            var text = "3.";
            var token = Lex(text).First();

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal("3", token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericFloatWithLeadingDecimalPoint()
        {
            var value = .3;
            var text = ".3";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericExponentWithoutDecimalPoint()
        {
            var value = 3e1;
            var text = "3e1";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        [Trait("Feature", "Literals")]
        public void TestNumericExponentWithNegative()
        {
            var value = 3e-1;
            var text = "3e-1";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(value, token.Value);
        }

        [Fact]
        public void TestDottedNameSequence()
        {
            var results = this.Blend("T.X.Y").ToList();
            Assert.Equal(6, results.Count);
        }

        [Fact]
        public void TestDebuggerDollarIdentifiers()
        {
            string text = "$";
            var token = DebuggerLexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(text, token.Value);

            text = "$x";
            token = DebuggerLexToken(text);
            errors = token.Errors();

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(text, token.Value);

            text = "x$";
            token = DebuggerLexToken(text);
            errors = token.Errors();

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(0, errors.Length);
            Assert.Equal(text.Substring(0, text.Length - 1), token.Text);
            Assert.Equal(text.Substring(0, text.Length - 1), token.Value);
        }

        [Fact]
        public void TestDebuggerObjectAddressIdentifiers()
        {
            var token = Lex("@0x0").First();
            Assert.Equal(SyntaxKind.BadToken, token.Kind());
            VerifyError(token, ErrorCode.ERR_ExpectedVerbatimLiteral);
            Assert.Equal("@", token.Text);
            Assert.Equal("@", token.Value);

            token = DebuggerLexToken("@0x0");
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            VerifyNoErrors(token);
            Assert.Equal("@0x0", token.Text);
            Assert.Equal("0x0", token.Value);

            token = DebuggerLexToken("@0X012345678");
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            VerifyNoErrors(token);
            Assert.Equal("@0X012345678", token.Text);
            Assert.Equal("0X012345678", token.Value);

            token = DebuggerLexToken("@0x9abcdefA");
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            VerifyNoErrors(token);
            Assert.Equal("@0x9abcdefA", token.Text);
            Assert.Equal("0x9abcdefA", token.Value);

            token = DebuggerLexToken("@0xBCDEF");
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            VerifyNoErrors(token);
            Assert.Equal("@0xBCDEF", token.Text);
            Assert.Equal("0xBCDEF", token.Value);

            token = DebuggerLexToken("@0x");
            Assert.Equal(SyntaxKind.BadToken, token.Kind());
            VerifyError(token, ErrorCode.ERR_ExpectedVerbatimLiteral);
            Assert.Equal("@", token.Text);
            Assert.Equal("@", token.Value);

            token = Lex("@0b1c2d3e4f").First();
            Assert.Equal(SyntaxKind.BadToken, token.Kind());
            VerifyError(token, ErrorCode.ERR_ExpectedVerbatimLiteral);
            Assert.Equal("@", token.Text);
            Assert.Equal("@", token.Value);

            token = DebuggerLexToken("@0b1c2d3e4f");
            Assert.Equal(SyntaxKind.BadToken, token.Kind());
            VerifyError(token, ErrorCode.ERR_ExpectedVerbatimLiteral);
            Assert.Equal("@", token.Text);
            Assert.Equal("@", token.Value);

            token = DebuggerLexToken("@0x12u");
            Assert.Equal(SyntaxKind.BadToken, token.Kind());
            VerifyError(token, ErrorCode.ERR_ExpectedVerbatimLiteral);
            Assert.Equal("@", token.Text);
            Assert.Equal("@", token.Value);

            token = DebuggerLexToken("@0xffff0000ffff0000ffff0000");
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            VerifyError(token, ErrorCode.ERR_IntOverflow);
            Assert.Equal("@0xffff0000ffff0000ffff0000", token.Text);
            Assert.Equal("0xffff0000ffff0000ffff0000", token.Value);
        }

        /// <summary>
        /// Earlier identifier syntax "[0-9]+#" not supported.
        /// </summary>
        [WorkItem(1071347, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/1071347")]
        [Fact]
        public void TestDebuggerAliasIdentifiers()
        {
            string text = "123#";
            var token = DebuggerLexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_LegacyObjectIdSyntax, errors[0].Code);
            Assert.Equal("error CS2043: 'id#' syntax is no longer supported. Use '$id' instead.", errors[0].ToString(EnsureEnglishUICulture.PreferredOrNull));
            Assert.Equal(text, token.Text);
            Assert.Equal(text, token.Value);

            text = "0123#";
            token = DebuggerLexToken(text);
            errors = token.Errors();

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(1, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal(text, token.Value);

            text = "0x123#";
            token = DebuggerLexToken(text);
            errors = token.Errors();

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(1, errors.Length);
            Assert.Equal(text.Substring(0, text.Length - 1), token.Text);
            Assert.Equal(0x123, token.Value);

            text = "123L#";
            token = DebuggerLexToken(text);
            errors = token.Errors();

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(1, errors.Length);
            Assert.Equal(text.Substring(0, text.Length - 1), token.Text);
            Assert.Equal(123L, token.Value);

            // Current syntax.
            text = "$123";
            token = DebuggerLexToken(text);
            errors = token.Errors();

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal(0, errors.Length);
            Assert.Equal(text, token.Text);
            Assert.Equal("$123", token.Value);
        }

        [Fact]
        public void TestWhitespace()
        {
            string text = " \t\v\f\u00A0token\u00A0\f\v\t ";
            var token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal("token", token.Text);
            Assert.True(token.HasLeadingTrivia);
            var leading = token.GetLeadingTrivia();
            Assert.Equal(1, leading.Count);
            Assert.Equal(SyntaxKind.WhitespaceTrivia, leading[0].Kind());
            Assert.Equal(" \t\v\f\u00A0", leading[0].ToString());

            Assert.True(token.HasTrailingTrivia);
            var trailing = token.GetTrailingTrivia();
            Assert.Equal(1, trailing.Count);
            Assert.Equal(SyntaxKind.WhitespaceTrivia, trailing[0].Kind());
            Assert.Equal("\u00A0\f\v\t ", trailing[0].ToString());

            text = "\u001Atoken\u001A";
            token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal("token", token.Text);
            Assert.True(token.HasLeadingTrivia);
            leading = token.GetLeadingTrivia();
            Assert.Equal(1, leading.Count);
            Assert.Equal(SyntaxKind.WhitespaceTrivia, leading[0].Kind());
            Assert.Equal("\u001A", leading[0].ToString());

            Assert.True(token.HasTrailingTrivia);
            trailing = token.GetTrailingTrivia();
            Assert.Equal(1, trailing.Count);
            Assert.Equal(SyntaxKind.WhitespaceTrivia, trailing[0].Kind());
            Assert.Equal("\u001A", trailing[0].ToString());

            // BOM is special. It is both whitespace and an identifier character.

            text = "\uFEFFto\uFEFFken\uFEFF \uFEFF";
            token = LexToken(text);

            Assert.NotEqual(default, token);
            Assert.Equal(SyntaxKind.IdentifierToken, token.Kind());
            Assert.Equal("to\uFEFFken\uFEFF", token.Text);
            Assert.Equal("token", token.Value);
            Assert.True(token.HasLeadingTrivia);
            leading = token.GetLeadingTrivia();
            Assert.Equal(1, leading.Count);
            Assert.Equal(SyntaxKind.WhitespaceTrivia, leading[0].Kind());
            Assert.Equal("\uFEFF", leading[0].ToString());

            Assert.True(token.HasTrailingTrivia);
            trailing = token.GetTrailingTrivia();
            Assert.Equal(1, trailing.Count);
            Assert.Equal(SyntaxKind.WhitespaceTrivia, trailing[0].Kind());
            Assert.Equal(" \uFEFF", trailing[0].ToString());
        }

        [Fact]
        public void DecimalLiterals()
        {
            // Max value is 79228162514264337593543950335

            // Push boundary at various precisions.
            AssertGoodDecimalLiteral("7e28m", "70000000b30310a7e22ea49300000000");
            AssertBadDecimalLiteral("8e28m"); //too large

            AssertGoodDecimalLiteral("792E26m", "600000000ae7ac71ffe8b45b00000000");
            AssertBadDecimalLiteral("793E26m"); //too large

            AssertGoodDecimalLiteral("7922816251426433759354395033E1m", "fffffffaffffffffffffffff00000000");
            AssertBadDecimalLiteral("7922816251426433759354395034E1m"); //too large

            // Exact boundary with various scales
            AssertGoodDecimalLiteral("79228162514264337593543950335E0m", "ffffffffffffffffffffffff00000000");
            AssertBadDecimalLiteral("79228162514264337593543950346E0m"); //too large

            AssertGoodDecimalLiteral("7922816251426433759354395033.5E1m", "ffffffffffffffffffffffff00000000");
            AssertBadDecimalLiteral("7922816251426433759354395034.6E1m"); //too large

            AssertGoodDecimalLiteral("7.9228162514264337593543950335E28m", "ffffffffffffffffffffffff00000000");
            AssertBadDecimalLiteral("7.9228162514264337593543950346E28m"); //too large

            // Exponent has too many digits.
            AssertBadDecimalLiteral("1e9999M");
            AssertGoodDecimalLiteral("1e-9999M", "000000000000000000000000001c0000"); // Native compiler reports CS0594
            AssertBadDecimalLiteral("1.0e9999M");
            AssertGoodDecimalLiteral("1.0e-9999M", "000000000000000000000000001c0000"); // Native compiler reports CS0594

            // Exponent has way too many digits.
            AssertBadDecimalLiteral("1e99999999999999999999999999M");
            AssertGoodDecimalLiteral("1e-99999999999999999999999999M", "000000000000000000000000001c0000"); // Native compiler reports CS0594
            AssertBadDecimalLiteral("1.0e99999999999999999999999999M");
            AssertGoodDecimalLiteral("1.0e-99999999999999999999999999M", "000000000000000000000000001c0000"); // Native compiler reports CS0594

            // Zeroes with precision.
            AssertGoodDecimalLiteral("0e-27M", "000000000000000000000000001b0000");
            AssertGoodDecimalLiteral("0e-28M", "000000000000000000000000001c0000");
            AssertGoodDecimalLiteral("0e-29M", "000000000000000000000000001c0000"); //CONSIDER: dev10 has 00000000000000000000000000000000, which makes no sense

            // Silent underflow.
            AssertGoodDecimalLiteral("1e-27M", "000000010000000000000000001b0000");
            AssertGoodDecimalLiteral("1e-28M", "000000010000000000000000001c0000");
            AssertGoodDecimalLiteral("1e-29M", "000000000000000000000000001c0000"); //Becomes zero.
        }

        [Fact]
        public void DecimalLiteralsManyDigits()
        {
            AssertGoodDecimalLiteral("1.23456789012345678901234567890123456789012345678901234567890e28m", "6e39811546bec9b127e41b3200000000");
            AssertBadDecimalLiteral("1.23456789012345678901234567890123456789012345678901234567890e29m");
            AssertGoodDecimalLiteral("123456789012345678901234567890123456789012345678901234567890e-31m", "6e39811546bec9b127e41b3200000000");
            AssertBadDecimalLiteral("123456789012345678901234567890123456789012345678901234567890e-30m");
            AssertGoodDecimalLiteral("123456789012345678901234567890.123456789012345678901234567890e-1m", "6e39811546bec9b127e41b3200000000");
            AssertBadDecimalLiteral("123456789012345678901234567890.123456789012345678901234567890e-0m");
        }

        [Fact]
        public void MoreDecimalLiterals()
        {
            // Max value is 79228162514264337593543950335

            AssertGoodDecimalLiteral("792281625142643375935439503350E-1M", "ffffffffffffffffffffffff00000000");
            AssertGoodDecimalLiteral("7922816251426433759354395033500000E-5M", "ffffffffffffffffffffffff00000000");

            AssertGoodDecimalLiteral("792281625142643375935439503354E-1M", "ffffffffffffffffffffffff00000000");
            AssertGoodDecimalLiteral("7922816251426433759354395033549999E-5M", "ffffffffffffffffffffffff00000000");
        }

        [Fact]
        public void TestMaxKeywordLength()
        {
            int max = SyntaxFacts
                .GetKeywordKinds()
                .Concat(SyntaxFacts.GetContextualKeywordKinds())
                .Select(SyntaxFacts.GetText)
                .Max(x => x.Length);
            Assert.Equal(LexerCache.MaxKeywordLength, max);
        }

        [WorkItem(545781, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/545781")]
        [Fact]
        public void DecimalLiteralsOtherCulture()
        {
            var oldCulture = CultureInfo.CurrentCulture;
            try
            {
                CultureInfo.CurrentCulture = (CultureInfo)oldCulture.Clone();
                CultureInfo.CurrentCulture.NumberFormat.NegativeSign = "~";
                CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator = ",";

                // If the exponent ("-1") is parsed using the current culture, then
                // parsing will raise a FormatException because the current culture
                // uses '~' as a negative sign.  Not seeing an exception ensures that
                // we are parsing with the invariant culture.
                AssertGoodDecimalLiteral("1.1E-1M", "0000000b000000000000000000020000");
            }
            finally
            {
                CultureInfo.CurrentCulture = oldCulture;
            }
        }

        private void AssertBadDecimalLiteral(string text)
        {
            var token = LexToken(text);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            var error = token.Errors().Single();
            Assert.Equal((int)ErrorCode.ERR_FloatOverflow, error.Code);
        }

        private void AssertGoodDecimalLiteral(string text, string expectedBits)
        {
            var token = LexToken(text);
            Assert.Equal(SyntaxKind.NumericLiteralToken, token.Kind());
            Assert.Equal(0, token.Errors().Length);
            Assert.Equal(expectedBits, ToHexString((decimal)token.Value));
        }

        private static void VerifyNoErrors(SyntaxToken token)
        {
            var errors = token.Errors();
            Assert.Equal(0, errors.Length);
        }

        private static void VerifyError(SyntaxToken token, ErrorCode expected)
        {
            var errors = token.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)expected, errors[0].Code);
        }

        private static string ToHexString(decimal d)
        {
            return string.Join("", decimal.GetBits(d).Select(word => string.Format("{0:x8}", word)));
        }

        [Fact]
        public void TestGreaterThanConflictMarkerNotConsumedWhenLegalInGeneric()
        {
            var source = @"
class C
{
    void M()
    {
        var v = new List<List<List<List<List<List<List<int
>>>>>>> 
();
    }
}";
            var tree = CSharpSyntaxTree.ParseText(source);
            var diagnostics = tree.GetDiagnostics();
            Assert.Empty(diagnostics);

            Assert.False(tree.GetRoot().DescendantTokens().Any(
                t => t.LeadingTrivia.Any(SyntaxKind.ConflictMarkerTrivia) ||
                     t.TrailingTrivia.Any(SyntaxKind.ConflictMarkerTrivia)));
        }

        [Fact]
        public void TestLessThanConflictMarker1()
        {
            // Needs to be followed by a space.
            var token = Lex("<<<<<<<").First();
            Assert.Equal(SyntaxKind.LessThanLessThanToken, token.Kind());

            // Has to be the start of a line.
            token = Lex(" <<<<<<<").First();
            Assert.Equal(SyntaxKind.LessThanLessThanToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.True(token.LeadingTrivia.Single().Kind() == SyntaxKind.WhitespaceTrivia);

            // Has to have at least seven characters.
            token = Lex("<<<<<< ").First();
            Assert.Equal(SyntaxKind.LessThanLessThanToken, token.Kind());

            // Start of line, seven characters, ends with space.
            token = Lex("<<<<<<< ").First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            var trivia = token.LeadingTrivia.Single();
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);

            Assert.True(trivia.ContainsDiagnostics);
            var errors = trivia.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, errors[0].Code);
        }

        [Fact]
        public void TestLessThanConflictMarker2()
        {
            var token = Lex("{\r\n<<<<<<<").Skip(1).First();
            Assert.Equal(SyntaxKind.LessThanLessThanToken, token.Kind());

            token = Lex("{\r\n <<<<<<<").Skip(1).First();
            Assert.Equal(SyntaxKind.LessThanLessThanToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.True(token.LeadingTrivia.Single().Kind() == SyntaxKind.WhitespaceTrivia);

            token = Lex("{\r\n<<<<<< ").Skip(1).First();
            Assert.Equal(SyntaxKind.LessThanLessThanToken, token.Kind());

            token = Lex("{\r\n<<<<<<< ").Skip(1).First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            var trivia = token.LeadingTrivia.Single();
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.True(trivia.SpanStart == 3);
            Assert.True(trivia.Span.Length == 8);

            Assert.True(trivia.ContainsDiagnostics);
            var errors = trivia.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, errors[0].Code);
        }

        [Fact]
        public void TestGreaterThanConflictMarker1()
        {
            // Less-than's should never be merged as conflict markers, except if they follow
            // an ======= region

            var token = Lex(">>>>>>>").First();
            Assert.Equal(SyntaxKind.GreaterThanToken, token.Kind());

            token = Lex(" >>>>>>>").First();
            Assert.Equal(SyntaxKind.GreaterThanToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.True(token.LeadingTrivia.Single().Kind() == SyntaxKind.WhitespaceTrivia);

            token = Lex(">>>>>> ").First();
            Assert.Equal(SyntaxKind.GreaterThanToken, token.Kind());

            token = Lex(">>>>>>> ").First();
            Assert.Equal(SyntaxKind.GreaterThanToken, token.Kind());

            Assert.False(token.ContainsDiagnostics);
        }

        [Fact]
        public void TestGreaterThanConflictMarker2()
        {
            // Less-than's should never be merged as conflict markers, except if they follow
            // an ======= region

            var token = Lex("{\r\n>>>>>>>").Skip(1).First();
            Assert.Equal(SyntaxKind.GreaterThanToken, token.Kind());

            token = Lex("{\r\n >>>>>>>").Skip(1).First();
            Assert.Equal(SyntaxKind.GreaterThanToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.True(token.LeadingTrivia.Single().Kind() == SyntaxKind.WhitespaceTrivia);

            token = Lex("{\r\n>>>>>> ").Skip(1).First();
            Assert.Equal(SyntaxKind.GreaterThanToken, token.Kind());

            token = Lex("{\r\n>>>>>>> ").Skip(1).First();
            Assert.Equal(SyntaxKind.GreaterThanToken, token.Kind());

            Assert.False(token.ContainsDiagnostics);
        }

        [Fact]
        public void TestEqualsConflictMarker1()
        {
            // Has to be the start of a line.
            var token = Lex(" =======").First();
            Assert.Equal(SyntaxKind.EqualsEqualsToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.True(token.LeadingTrivia.Single().Kind() == SyntaxKind.WhitespaceTrivia);

            // Has to have at least seven characters.
            token = Lex("====== ").First();
            Assert.Equal(SyntaxKind.EqualsEqualsToken, token.Kind());

            // Start of line, seven characters
            token = Lex("=======").First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.True(token.LeadingTrivia.Single().Kind() == SyntaxKind.ConflictMarkerTrivia);

            // Start of line, seven characters
            token = Lex("======= trailing chars").First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            var trivia = token.LeadingTrivia.Single();
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal(22, trivia.Span.Length);

            Assert.True(trivia.ContainsDiagnostics);
            var errors = trivia.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, errors[0].Code);

            token = Lex("======= Trailing\r\ndisabled text").First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.Equal(3, token.LeadingTrivia.Count);
            trivia = token.LeadingTrivia[0];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal(16, trivia.Span.Length);

            Assert.True(trivia.ContainsDiagnostics);
            errors = trivia.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, errors[0].Code);

            trivia = token.LeadingTrivia[1];
            Assert.True(trivia.Kind() == SyntaxKind.EndOfLineTrivia);
            Assert.Equal(16, trivia.Span.Start);
            Assert.Equal(2, trivia.Span.Length);

            trivia = token.LeadingTrivia[2];
            Assert.True(trivia.Kind() == SyntaxKind.DisabledTextTrivia);
            Assert.Equal(18, trivia.Span.Start);
            Assert.Equal(13, trivia.Span.Length);

            token = Lex("======= Trailing\r\ndisabled text\r\n>>>> still disabled").First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.Equal(3, token.LeadingTrivia.Count);

            trivia = token.LeadingTrivia[0];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal(16, trivia.Span.Length);

            Assert.True(trivia.ContainsDiagnostics);
            errors = trivia.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, errors[0].Code);

            trivia = token.LeadingTrivia[1];
            Assert.True(trivia.Kind() == SyntaxKind.EndOfLineTrivia);
            Assert.Equal(2, trivia.Span.Length);

            trivia = token.LeadingTrivia[2];
            Assert.True(trivia.Kind() == SyntaxKind.DisabledTextTrivia);
            Assert.Equal(34, trivia.Span.Length);

            token = Lex("======= Trailing\r\ndisabled text\r\n>>>>>>> Actually the end").First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.Equal(4, token.LeadingTrivia.Count);
            var trivia1 = token.LeadingTrivia[0];
            Assert.True(trivia1.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal(16, trivia1.Span.Length);

            Assert.True(trivia1.ContainsDiagnostics);
            errors = trivia1.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, errors[0].Code);

            var trivia2 = token.LeadingTrivia[1];
            Assert.True(trivia2.Kind() == SyntaxKind.EndOfLineTrivia);
            Assert.Equal(16, trivia2.Span.Start);
            Assert.Equal(2, trivia2.Span.Length);

            var trivia3 = token.LeadingTrivia[2];
            Assert.True(trivia3.Kind() == SyntaxKind.DisabledTextTrivia);
            Assert.Equal(18, trivia3.Span.Start);
            Assert.Equal(15, trivia3.Span.Length);

            var trivia4 = token.LeadingTrivia[3];
            Assert.True(trivia4.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal(33, trivia4.Span.Start);
            Assert.Equal(24, trivia4.Span.Length);

            Assert.True(trivia4.ContainsDiagnostics);
            errors = trivia4.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, errors[0].Code);

            token = Lex("======= Trailing\r\n>>>>>>> Actually the end").First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.Equal(3, token.LeadingTrivia.Count);
            trivia1 = token.LeadingTrivia[0];
            Assert.True(trivia1.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal(16, trivia1.Span.Length);

            Assert.True(trivia1.ContainsDiagnostics);
            errors = trivia1.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, errors[0].Code);

            trivia2 = token.LeadingTrivia[1];
            Assert.True(trivia2.Kind() == SyntaxKind.EndOfLineTrivia);
            Assert.Equal(16, trivia2.Span.Start);
            Assert.Equal(2, trivia2.Span.Length);

            trivia3 = token.LeadingTrivia[2];
            Assert.True(trivia3.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal(18, trivia3.Span.Start);
            Assert.Equal(24, trivia3.Span.Length);

            Assert.True(trivia3.ContainsDiagnostics);
            errors = trivia3.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, errors[0].Code);
        }

        [Fact]
        public void TestEqualsConflictMarker2()
        {
            // Has to be the start of a line.
            var token = Lex("{\r\n =======").Skip(1).First();
            Assert.Equal(SyntaxKind.EqualsEqualsToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.True(token.LeadingTrivia.Single().Kind() == SyntaxKind.WhitespaceTrivia);

            // Has to have at least seven characters.
            token = Lex("{\r\n====== ").Skip(1).First();
            Assert.Equal(SyntaxKind.EqualsEqualsToken, token.Kind());

            // Start of line, seven characters
            token = Lex("{\r\n=======").Skip(1).First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.True(token.LeadingTrivia.Single().Kind() == SyntaxKind.ConflictMarkerTrivia);

            // Start of line, seven characters
            token = Lex("{\r\n======= trailing chars").Skip(1).First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            var trivia = token.LeadingTrivia.Single();
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal(22, trivia.Span.Length);

            token = Lex("{\r\n======= Trailing\r\ndisabled text").Skip(1).First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.Equal(3, token.LeadingTrivia.Count);
            trivia = token.LeadingTrivia[0];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal(16, trivia.Span.Length);

            trivia = token.LeadingTrivia[1];
            Assert.True(trivia.Kind() == SyntaxKind.EndOfLineTrivia);
            Assert.Equal(19, trivia.Span.Start);
            Assert.Equal(2, trivia.Span.Length);

            trivia = token.LeadingTrivia[2];
            Assert.True(trivia.Kind() == SyntaxKind.DisabledTextTrivia);
            Assert.Equal(21, trivia.Span.Start);
            Assert.Equal(13, trivia.Span.Length);

            token = Lex("{\r\n======= Trailing\r\ndisabled text\r\n>>>> still disabled").Skip(1).First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.Equal(3, token.LeadingTrivia.Count);

            trivia = token.LeadingTrivia[0];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal(16, trivia.Span.Length);

            trivia = token.LeadingTrivia[1];
            Assert.True(trivia.Kind() == SyntaxKind.EndOfLineTrivia);
            Assert.Equal(2, trivia.Span.Length);

            trivia = token.LeadingTrivia[2];
            Assert.True(trivia.Kind() == SyntaxKind.DisabledTextTrivia);
            Assert.Equal(34, trivia.Span.Length);

            token = Lex("{\r\n======= Trailing\r\ndisabled text\r\n>>>>>>> Actually the end").Skip(1).First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.Equal(4, token.LeadingTrivia.Count);
            var trivia1 = token.LeadingTrivia[0];
            Assert.True(trivia1.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal(16, trivia1.Span.Length);

            var trivia2 = token.LeadingTrivia[1];
            Assert.True(trivia2.Kind() == SyntaxKind.EndOfLineTrivia);
            Assert.Equal(19, trivia2.Span.Start);
            Assert.Equal(2, trivia2.Span.Length);

            var trivia3 = token.LeadingTrivia[2];
            Assert.True(trivia3.Kind() == SyntaxKind.DisabledTextTrivia);
            Assert.Equal(21, trivia3.Span.Start);
            Assert.Equal(15, trivia3.Span.Length);

            var trivia4 = token.LeadingTrivia[3];
            Assert.True(trivia4.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal(36, trivia4.Span.Start);
            Assert.Equal(24, trivia4.Span.Length);
        }

        [Fact]
        public void TestEqualsConflictMarker3()
        {
            // second ======= is part of disabled text
            var token = Lex("""
                ======= Trailing
                disabled text 2
                ======= 
                more disabled text
                >>>>>>> Actually the end
                """).First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.Equal(4, token.LeadingTrivia.Count);

            var trivia = token.LeadingTrivia[0];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal("======= Trailing", trivia.ToFullString());
            Assert.True(trivia.ContainsDiagnostics);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, trivia.Errors().Single().Code);

            trivia = token.LeadingTrivia[1];
            Assert.True(trivia.Kind() == SyntaxKind.EndOfLineTrivia);

            trivia = token.LeadingTrivia[2];
            Assert.True(trivia.Kind() == SyntaxKind.DisabledTextTrivia);
            Assert.Equal("""
                disabled text 2
                ======= 
                more disabled text

                """, trivia.ToFullString());

            trivia = token.LeadingTrivia[3];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal(">>>>>>> Actually the end", trivia.ToFullString());
            Assert.True(trivia.ContainsDiagnostics);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, trivia.Errors().Single().Code);
        }

        [Fact]
        public void TestEqualsConflictMarker4()
        {
            // ||||||| is part of disabled text
            var token = Lex("""
                ======= Trailing
                disabled text 2
                ||||||| 
                more disabled text
                >>>>>>> Actually the end
                """).First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.Equal(4, token.LeadingTrivia.Count);

            var trivia = token.LeadingTrivia[0];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal("======= Trailing", trivia.ToFullString());
            Assert.True(trivia.ContainsDiagnostics);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, trivia.Errors().Single().Code);

            trivia = token.LeadingTrivia[1];
            Assert.True(trivia.Kind() == SyntaxKind.EndOfLineTrivia);

            trivia = token.LeadingTrivia[2];
            Assert.True(trivia.Kind() == SyntaxKind.DisabledTextTrivia);
            Assert.Equal("""
                disabled text 2
                ||||||| 
                more disabled text

                """, trivia.ToFullString());

            trivia = token.LeadingTrivia[3];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal(">>>>>>> Actually the end", trivia.ToFullString());
            Assert.True(trivia.ContainsDiagnostics);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, trivia.Errors().Single().Code);
        }

        [Fact]
        public void TestPipeConflictMarker1()
        {
            // Has to be the start of a line.
            var token = Lex(" |||||||").First();
            Assert.Equal(SyntaxKind.BarBarToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.True(token.LeadingTrivia.Single().Kind() == SyntaxKind.WhitespaceTrivia);

            // Has to have at least seven characters.
            token = Lex("|||||| ").First();
            Assert.Equal(SyntaxKind.BarBarToken, token.Kind());

            // Start of line, seven characters
            token = Lex("|||||||").First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.True(token.LeadingTrivia.Single().Kind() == SyntaxKind.ConflictMarkerTrivia);

            // Start of line, seven characters
            token = Lex("||||||| trailing chars").First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            var trivia = token.LeadingTrivia.Single();
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);

            Assert.True(trivia.ContainsDiagnostics);
            var errors = trivia.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, errors[0].Code);

            token = Lex("""
                ||||||| Trailing
                disabled text
                """).First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.Equal(3, token.LeadingTrivia.Count);
            trivia = token.LeadingTrivia[0];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);

            Assert.True(trivia.ContainsDiagnostics);
            errors = trivia.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, errors[0].Code);

            trivia = token.LeadingTrivia[1];
            Assert.True(trivia.Kind() == SyntaxKind.EndOfLineTrivia);

            trivia = token.LeadingTrivia[2];
            Assert.True(trivia.Kind() == SyntaxKind.DisabledTextTrivia);

            token = Lex("""
                ||||||| Trailing
                disabled text
                >>>> still disabled
                """).First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.Equal(3, token.LeadingTrivia.Count);

            trivia = token.LeadingTrivia[0];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);

            Assert.True(trivia.ContainsDiagnostics);
            errors = trivia.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, errors[0].Code);

            trivia = token.LeadingTrivia[1];
            Assert.True(trivia.Kind() == SyntaxKind.EndOfLineTrivia);

            trivia = token.LeadingTrivia[2];
            Assert.True(trivia.Kind() == SyntaxKind.DisabledTextTrivia);

            token = Lex("""
                ||||||| Trailing
                disabled text
                >>>>>>> Actually the end
                """).First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.Equal(4, token.LeadingTrivia.Count);
            var trivia1 = token.LeadingTrivia[0];
            Assert.True(trivia1.Kind() == SyntaxKind.ConflictMarkerTrivia);

            Assert.True(trivia1.ContainsDiagnostics);
            errors = trivia1.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, errors[0].Code);

            var trivia2 = token.LeadingTrivia[1];
            Assert.True(trivia2.Kind() == SyntaxKind.EndOfLineTrivia);

            var trivia3 = token.LeadingTrivia[2];
            Assert.True(trivia3.Kind() == SyntaxKind.DisabledTextTrivia);

            var trivia4 = token.LeadingTrivia[3];
            Assert.True(trivia4.Kind() == SyntaxKind.ConflictMarkerTrivia);

            Assert.True(trivia4.ContainsDiagnostics);
            errors = trivia4.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, errors[0].Code);

            token = Lex("""
                ||||||| Trailing
                >>>>>>> Actually the end
                """).First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.Equal(3, token.LeadingTrivia.Count);
            trivia1 = token.LeadingTrivia[0];
            Assert.True(trivia1.Kind() == SyntaxKind.ConflictMarkerTrivia);

            Assert.True(trivia1.ContainsDiagnostics);
            errors = trivia1.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, errors[0].Code);

            trivia2 = token.LeadingTrivia[1];
            Assert.True(trivia2.Kind() == SyntaxKind.EndOfLineTrivia);

            trivia3 = token.LeadingTrivia[2];
            Assert.True(trivia3.Kind() == SyntaxKind.ConflictMarkerTrivia);

            Assert.True(trivia3.ContainsDiagnostics);
            errors = trivia3.Errors();
            Assert.Equal(1, errors.Length);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, errors[0].Code);
        }

        [Fact]
        public void TestPipeConflictMarker2()
        {
            var token = Lex("""
                ||||||| Mid
                ======= Trailing
                >>>>>>> Actually the end
                """).First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.Equal(5, token.LeadingTrivia.Count);

            var trivia = token.LeadingTrivia[0];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal("||||||| Mid", trivia.ToFullString());
            Assert.True(trivia.ContainsDiagnostics);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, trivia.Errors().Single().Code);

            trivia = token.LeadingTrivia[1];
            Assert.True(trivia.Kind() == SyntaxKind.EndOfLineTrivia);

            trivia = token.LeadingTrivia[2];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal("======= Trailing", trivia.ToFullString());
            Assert.True(trivia.ContainsDiagnostics);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, trivia.Errors().Single().Code);

            trivia = token.LeadingTrivia[3];
            Assert.True(trivia.Kind() == SyntaxKind.EndOfLineTrivia);

            trivia = token.LeadingTrivia[4];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal(">>>>>>> Actually the end", trivia.ToFullString());
            Assert.True(trivia.ContainsDiagnostics);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, trivia.Errors().Single().Code);
        }

        [Fact]
        public void TestPipeConflictMarker3()
        {
            var token = Lex("""
                ||||||| Mid
                disabled text 1
                ======= Trailing
                disabled text 2
                >>>>>>> Actually the end
                """).First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.Equal(7, token.LeadingTrivia.Count);

            var trivia = token.LeadingTrivia[0];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal("||||||| Mid", trivia.ToFullString());
            Assert.True(trivia.ContainsDiagnostics);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, trivia.Errors().Single().Code);

            trivia = token.LeadingTrivia[1];
            Assert.True(trivia.Kind() == SyntaxKind.EndOfLineTrivia);

            trivia = token.LeadingTrivia[2];
            Assert.True(trivia.Kind() == SyntaxKind.DisabledTextTrivia);
            Assert.Equal("""
                disabled text 1

                """, trivia.ToFullString());

            trivia = token.LeadingTrivia[3];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal("======= Trailing", trivia.ToFullString());
            Assert.True(trivia.ContainsDiagnostics);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, trivia.Errors().Single().Code);

            trivia = token.LeadingTrivia[4];
            Assert.True(trivia.Kind() == SyntaxKind.EndOfLineTrivia);

            trivia = token.LeadingTrivia[5];
            Assert.True(trivia.Kind() == SyntaxKind.DisabledTextTrivia);
            Assert.Equal("""
                disabled text 2

                """, trivia.ToFullString());

            trivia = token.LeadingTrivia[6];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal(">>>>>>> Actually the end", trivia.ToFullString());
            Assert.True(trivia.ContainsDiagnostics);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, trivia.Errors().Single().Code);
        }

        [Fact]
        public void TestPipeConflictMarker4()
        {
            // second ======= is pat of disabled text
            var token = Lex("""
                ||||||| Mid
                disabled text 1
                ======= Trailing
                disabled text 2
                ======= 
                more disabled text
                >>>>>>> Actually the end
                """).First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.Equal(7, token.LeadingTrivia.Count);

            var trivia = token.LeadingTrivia[0];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal("||||||| Mid", trivia.ToFullString());
            Assert.True(trivia.ContainsDiagnostics);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, trivia.Errors().Single().Code);

            trivia = token.LeadingTrivia[1];
            Assert.True(trivia.Kind() == SyntaxKind.EndOfLineTrivia);

            trivia = token.LeadingTrivia[2];
            Assert.True(trivia.Kind() == SyntaxKind.DisabledTextTrivia);
            Assert.Equal("""
                disabled text 1

                """, trivia.ToFullString());

            trivia = token.LeadingTrivia[3];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal("======= Trailing", trivia.ToFullString());
            Assert.True(trivia.ContainsDiagnostics);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, trivia.Errors().Single().Code);

            trivia = token.LeadingTrivia[4];
            Assert.True(trivia.Kind() == SyntaxKind.EndOfLineTrivia);

            trivia = token.LeadingTrivia[5];
            Assert.True(trivia.Kind() == SyntaxKind.DisabledTextTrivia);
            Assert.Equal("""
                disabled text 2
                ======= 
                more disabled text

                """, trivia.ToFullString());

            trivia = token.LeadingTrivia[6];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal(">>>>>>> Actually the end", trivia.ToFullString());
            Assert.True(trivia.ContainsDiagnostics);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, trivia.Errors().Single().Code);
        }

        [Fact]
        public void TestPipeConflictMarker5()
        {
            // second ||||||| is pat of disabled text
            var token = Lex("""
                ||||||| Mid
                disabled text 1
                ||||||| 
                more disabled text
                ======= Trailing
                disabled text 2
                >>>>>>> Actually the end
                """).First();
            Assert.Equal(SyntaxKind.EndOfFileToken, token.Kind());
            Assert.True(token.HasLeadingTrivia);
            Assert.Equal(7, token.LeadingTrivia.Count);

            var trivia = token.LeadingTrivia[0];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal("||||||| Mid", trivia.ToFullString());
            Assert.True(trivia.ContainsDiagnostics);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, trivia.Errors().Single().Code);

            trivia = token.LeadingTrivia[1];
            Assert.True(trivia.Kind() == SyntaxKind.EndOfLineTrivia);

            trivia = token.LeadingTrivia[2];
            Assert.True(trivia.Kind() == SyntaxKind.DisabledTextTrivia);
            Assert.Equal("""
                disabled text 1
                ||||||| 
                more disabled text

                """, trivia.ToFullString());

            trivia = token.LeadingTrivia[3];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal("======= Trailing", trivia.ToFullString());
            Assert.True(trivia.ContainsDiagnostics);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, trivia.Errors().Single().Code);

            trivia = token.LeadingTrivia[4];
            Assert.True(trivia.Kind() == SyntaxKind.EndOfLineTrivia);

            trivia = token.LeadingTrivia[5];
            Assert.True(trivia.Kind() == SyntaxKind.DisabledTextTrivia);
            Assert.Equal("""
                disabled text 2

                """, trivia.ToFullString());

            trivia = token.LeadingTrivia[6];
            Assert.True(trivia.Kind() == SyntaxKind.ConflictMarkerTrivia);
            Assert.Equal(">>>>>>> Actually the end", trivia.ToFullString());
            Assert.True(trivia.ContainsDiagnostics);
            Assert.Equal((int)ErrorCode.ERR_Merge_conflict_marker_encountered, trivia.Errors().Single().Code);
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/78593")]
        public void TestDotPrefixedNumberStartingAtStartOfSlidingTextWindow()
        {
            // Make a file that looks effectively like:
            //
            //      ////// <long stream of slashes>
            //      ;
            //      ..0;
            //
            // We want both dots at the end of the window.  When we lex the first dot, we'll peek ahead to see if we're
            // on a number, and we don't want that to move the window forward.  Then when we lex the second dot, we will
            // peek forward, making the text window point at "0;".
            //
            // Because we will have seen `.0` we will attempt to peek backwards to see if the prior token was a dot.
            // This will involve reading back a chunk that includes that dot.
            var windowEnd = "\r\n;\r\n..";
            var code = new string('/', SlidingTextWindow.DefaultWindowLength - windowEnd.Length) + windowEnd + "0;";

            var sourceText = SourceText.From(code);

            {
                // Run a full parse, and validate the tree returned).

                using var lexer = new Lexer(sourceText, CSharpParseOptions.Default);

                using var parser = new LanguageParser(lexer, oldTree: null, changes: null);

                Microsoft.CodeAnalysis.SyntaxTreeExtensions.VerifySource(
                    sourceText, parser.ParseCompilationUnit().CreateRed());
            }

            {
                // Now, replicate the same conditions that hte parser runs through by driving the a new lexer here
                // directly.  That ensures that we are actually validating exactly the conditions that led to the bug
                // (a dot token starting a number, right at the start of the character window).
                var lexer = new Lexer(sourceText, CSharpParseOptions.Default);

                var mode = LexerMode.Syntax;
                var token1 = lexer.Lex(ref mode);
                Assert.Equal(SyntaxKind.SemicolonToken, token1.Kind);
                Assert.Equal(SlidingTextWindow.DefaultWindowLength - 2, token1.FullWidth);

                Assert.Equal(SlidingTextWindow.DefaultWindowLength - 2, SlidingTextWindow.TestAccessor.GetOffset(lexer.TextWindow));
                var token2 = lexer.Lex(ref mode);
                Assert.Equal(SyntaxKind.DotToken, token2.Kind);

                Assert.Equal(SlidingTextWindow.DefaultWindowLength - 1, SlidingTextWindow.TestAccessor.GetOffset(lexer.TextWindow));
                var token3 = lexer.Lex(ref mode);
                Assert.Equal(SyntaxKind.DotToken, token3.Kind);

                // We will have jumped the window backwards to be able to read the prior dot.
                Assert.Equal(code.IndexOf('.'), SlidingTextWindow.TestAccessor.GetCharacterWindowStartPositionInText(lexer.TextWindow));
                Assert.Equal(2, SlidingTextWindow.TestAccessor.GetOffset(lexer.TextWindow));
                Assert.StartsWith("..0;", SlidingTextWindow.TestAccessor.GetCharacterWindow(lexer.TextWindow).AsSpan().ToString());

                var token4 = lexer.Lex(ref mode);
                Assert.Equal(SyntaxKind.NumericLiteralToken, token4.Kind);
                Assert.Equal("0", token4.ValueText);
            }
        }
    }
}