test/Npgsql.Tests/ReaderTests.cs - test-logs - dev-npgsql/npgsql

test/Npgsql.Tests/ReaderTests.cs
2 732 строки113 KB
Nino Floris
Remove PgBufferedConverter virtual dispatch hop (#6574)
15 май 2026, 18:24
15 май 2026, 18:2478d37a1
using System;
using System.Buffers.Binary;
using System.Collections;
using System.Data;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Npgsql.BackendMessages;
using Npgsql.Internal;
using Npgsql.Internal.Postgres;
using Npgsql.PostgresTypes;
using Npgsql.Tests.Support;
using Npgsql.Util;
using NpgsqlTypes;
using NUnit.Framework;
using NUnit.Framework.Constraints;
using static Npgsql.Tests.TestUtil;

namespace Npgsql.Tests;

[TestFixture(CommandBehavior.Default)]
[TestFixture(CommandBehavior.SequentialAccess)]
public class ReaderTests : TestBase
{
    static uint Int4Oid => PostgresMinimalDatabaseInfo.DefaultTypeCatalog.GetOid(DataTypeNames.Int4).Value;
    static uint ByteaOid => PostgresMinimalDatabaseInfo.DefaultTypeCatalog.GetOid(DataTypeNames.Bytea).Value;

    [Test]
    public async Task Resumable_non_consumed_to_non_resumable()
    {
        await using var conn = await OpenConnectionAsync();
        await using var cmd = new NpgsqlCommand( "SELECT 'aaaaaaaa', 1", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);
        await reader.ReadAsync();

        await reader.IsDBNullAsync(0); // resumable, no consumption
        _ = reader.IsDBNull(0); // resumable, no consumption
        await using var stream = await reader.GetStreamAsync(0); // non-resumable
        if (IsSequential)
            Assert.That(() => reader.GetString(0), Throws.Exception.TypeOf<InvalidOperationException>());
    }

    [Test]
    public async Task Seek_columns()
    {
        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand("SELECT 1,2,3", conn);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        Assert.That(reader.Read(), Is.True);
        Assert.That(reader.GetInt32(0), Is.EqualTo(1));
        if (IsSequential)
            Assert.That(() => reader.GetInt32(0), Throws.Exception.TypeOf<InvalidOperationException>());
        else
            Assert.That(reader.GetInt32(0), Is.EqualTo(1));
        Assert.That(reader.GetInt32(1), Is.EqualTo(2));
        if (IsSequential)
            Assert.That(() => reader.GetInt32(0), Throws.Exception.TypeOf<InvalidOperationException>());
        else
            Assert.That(reader.GetInt32(0), Is.EqualTo(1));
    }

    [Test]
    public async Task No_resultset()
    {
        using var conn = await OpenConnectionAsync();
        var table = await CreateTempTable(conn, "id INT");

        using (var cmd = new NpgsqlCommand($"INSERT INTO {table} VALUES (8)", conn))
        using (var reader = await cmd.ExecuteReaderAsync(Behavior))
        {
            Assert.That(() => reader.GetOrdinal("foo"), Throws.Exception.TypeOf<InvalidOperationException>());
            Assert.That(reader.Read(), Is.False);
            Assert.That(() => reader.GetOrdinal("foo"), Throws.Exception.TypeOf<InvalidOperationException>());
            Assert.That(reader.FieldCount, Is.EqualTo(0));
            Assert.That(reader.NextResult(), Is.False);
            Assert.That(() => reader.GetOrdinal("foo"), Throws.Exception.TypeOf<InvalidOperationException>());
        }

        using (var cmd = new NpgsqlCommand($"SELECT 1; INSERT INTO {table} VALUES (8)", conn))
        using (var reader = await cmd.ExecuteReaderAsync(Behavior))
        {
            await reader.NextResultAsync();
            Assert.That(() => reader.GetOrdinal("foo"), Throws.Exception.TypeOf<InvalidOperationException>());
            Assert.That(reader.Read(), Is.False);
            Assert.That(() => reader.GetOrdinal("foo"), Throws.Exception.TypeOf<InvalidOperationException>());
            Assert.That(reader.FieldCount, Is.EqualTo(0));
        }
    }

    [Test]
    public async Task Empty_resultset()
    {
        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand("SELECT 1 AS foo WHERE FALSE", conn);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        Assert.That(reader.Read(), Is.False);
        Assert.That(reader.FieldCount, Is.EqualTo(1));
        Assert.That(reader.GetOrdinal("foo"), Is.EqualTo(0));
        Assert.That(() => reader[0], Throws.Exception.TypeOf<InvalidOperationException>());
    }

    [Test]
    public async Task FieldCount()
    {
        using var conn = await OpenConnectionAsync();
        var table = await CreateTempTable(conn, "int INT");

        using var cmd = new NpgsqlCommand("SELECT 1; SELECT 2,3", conn);
        using (var reader = await cmd.ExecuteReaderAsync(Behavior))
        {
            Assert.That(reader.FieldCount, Is.EqualTo(1));
            Assert.That(reader.Read(), Is.True);
            Assert.That(reader.FieldCount, Is.EqualTo(1));
            Assert.That(reader.Read(), Is.False);
            Assert.That(reader.FieldCount, Is.EqualTo(1));
            Assert.That(reader.NextResult(), Is.True);
            Assert.That(reader.FieldCount, Is.EqualTo(2));
            Assert.That(reader.NextResult(), Is.False);
            Assert.That(reader.FieldCount, Is.EqualTo(0));
        }

        cmd.CommandText = $"INSERT INTO {table} (int) VALUES (1)";
        using (var reader = await cmd.ExecuteReaderAsync(Behavior))
        {
            // Note MSDN docs that seem to say we should case -1 in this case: https://msdn.microsoft.com/en-us/library/system.data.idatarecord.fieldcount(v=vs.110).aspx
            // But SqlClient returns 0
            Assert.That(() => reader.FieldCount, Is.EqualTo(0));

        }
    }

    [Test]
    public async Task RecordsAffected()
    {
        using var conn = await OpenConnectionAsync();
        var table = await CreateTempTable(conn, "int INT");

        var sb = new StringBuilder();
        for (var i = 0; i < 10; i++)
            sb.Append($"INSERT INTO {table} (int) VALUES ({i});");
        sb.Append("SELECT 1;"); // Testing, that on close reader consumes all rows (as insert doesn't have a result set, but select does)
        for (var i = 10; i < 15; i++)
            sb.Append($"INSERT INTO {table} (int) VALUES ({i});");
        var cmd = new NpgsqlCommand(sb.ToString(), conn);
        var reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Close();
        Assert.That(reader.RecordsAffected, Is.EqualTo(15));

        cmd = new NpgsqlCommand($"SELECT * FROM {table}", conn);
        reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Close();
        Assert.That(reader.RecordsAffected, Is.EqualTo(-1));

        cmd = new NpgsqlCommand($"UPDATE {table} SET int=int+1 WHERE int > 10", conn);
        reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Close();
        Assert.That(reader.RecordsAffected, Is.EqualTo(4));

        cmd = new NpgsqlCommand($"UPDATE {table} SET int=8 WHERE int=666", conn);
        reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Close();
        Assert.That(reader.RecordsAffected, Is.EqualTo(0));

        cmd = new NpgsqlCommand($"DELETE FROM {table} WHERE int > 10", conn);
        reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Close();
        Assert.That(reader.RecordsAffected, Is.EqualTo(4));

        if (conn.PostgreSqlVersion.IsGreaterOrEqual(15))
        {
            cmd = new NpgsqlCommand($"MERGE INTO {table} S USING (SELECT 2 as int) T ON T.int = S.int WHEN MATCHED THEN UPDATE SET int = S.int", conn);
            reader = await cmd.ExecuteReaderAsync(Behavior);
            reader.Close();
            Assert.That(reader.RecordsAffected, Is.EqualTo(1));
        }
    }

#pragma warning disable CS0618
    [Test]
    public async Task StatementOID_legacy_batching()
    {
        using var conn = await OpenConnectionAsync();

        MaximumPgVersionExclusive(conn, "12.0",
            "Support for 'CREATE TABLE ... WITH OIDS' has been removed in 12.0. See https://www.postgresql.org/docs/12/release-12.html#id-1.11.6.5.4");

        var table = await GetTempTableName(conn);

        var query = $@"
CREATE TABLE {table} (name TEXT) WITH OIDS;
INSERT INTO {table} (name) VALUES ('a');
UPDATE {table} SET name='b' WHERE name='doesnt_exist';";

        using (var cmd = new NpgsqlCommand(query,conn))
        {
            using var reader = await cmd.ExecuteReaderAsync(Behavior);

            Assert.That(reader.Statements[0].OID, Is.EqualTo(0));
            Assert.That(reader.Statements[1].OID, Is.Not.EqualTo(0));
            Assert.That(reader.Statements[0].OID, Is.EqualTo(0));
        }

        using (var cmd = new NpgsqlCommand($"SELECT name FROM {table}; DELETE FROM {table}", conn))
        {
            using var reader = await cmd.ExecuteReaderAsync(Behavior);

            await reader.NextResultAsync(); // Consume SELECT result set
            Assert.That(reader.Statements[0].OID, Is.EqualTo(0));
            Assert.That(reader.Statements[1].OID, Is.EqualTo(0));
        }
    }
#pragma warning restore CS0618

    [Test]
    public async Task Get_string_with_parameter()
    {
        using var conn = await OpenConnectionAsync();
        var table = await CreateTempTable(conn, "name TEXT");
        const string text = "Random text";
        await conn.ExecuteNonQueryAsync($@"INSERT INTO {table} (name) VALUES ('{text}')");

        var command = new NpgsqlCommand($"SELECT name FROM {table} WHERE name = :value;", conn);
        var param = new NpgsqlParameter
        {
            ParameterName = "value",
            DbType = DbType.String,
            Size = text.Length,
            Value = text
        };
        //param.NpgsqlDbType = NpgsqlDbType.Text;
        command.Parameters.Add(param);

        using var dr = await command.ExecuteReaderAsync(Behavior);
        dr.Read();
        var result = dr.GetString(0);
        Assert.That(result, Is.EqualTo(text));
    }

    [Test]
    public async Task Get_string_with_quote_with_parameter()
    {
        using var conn = await OpenConnectionAsync();
        var table = await GetTempTableName(conn);
        await conn.ExecuteNonQueryAsync($@"
CREATE TABLE {table} (name TEXT);
INSERT INTO {table} (name) VALUES ('Text with '' single quote');");

        const string test = "Text with ' single quote";
        var command = new NpgsqlCommand($"SELECT name FROM {table} WHERE name = :value;", conn);

        var param = new NpgsqlParameter();
        param.ParameterName = "value";
        param.DbType = DbType.String;
        //param.NpgsqlDbType = NpgsqlDbType.Text;
        param.Size = test.Length;
        param.Value = test;
        command.Parameters.Add(param);

        using var dr = await command.ExecuteReaderAsync(Behavior);
        dr.Read();
        var result = dr.GetString(0);
        Assert.That(result, Is.EqualTo(test));
    }

    [Test]
    public async Task Get_value_by_name()
    {
        using var conn = await OpenConnectionAsync();
        using var command = new NpgsqlCommand(@"SELECT 'Random text' AS real_column", conn);
        using var dr = await command.ExecuteReaderAsync(Behavior);
        dr.Read();
        Assert.That(dr["real_column"], Is.EqualTo("Random text"));
        Assert.That(() => dr["non_existing"], Throws.Exception.TypeOf<IndexOutOfRangeException>());
    }

    [Test]
    [IssueLink("https://github.com/npgsql/npgsql/issues/794")]
    public async Task GetFieldType()
    {
        using var conn = await OpenConnectionAsync();
        using (var cmd = new NpgsqlCommand(@"SELECT 1::INT4 AS some_column", conn))
        using (var reader = await cmd.ExecuteReaderAsync(Behavior))
        {
            reader.Read();
            Assert.That(reader.GetFieldType(0), Is.SameAs(typeof(int)));
        }
        using (var cmd = new NpgsqlCommand(@"SELECT 1::INT4 AS some_column", conn))
        {
            cmd.AllResultTypesAreUnknown = true;
            using (var reader = await cmd.ExecuteReaderAsync(Behavior))
            {
                reader.Read();
                Assert.That(reader.GetFieldType(0), Is.SameAs(typeof(string)));
            }
        }
    }

    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/1096")]
    public async Task GetFieldType_SchemaOnly()
    {
        await using var conn = await OpenConnectionAsync();
        await using var cmd = new NpgsqlCommand(@"SELECT 1::INT4 AS some_column", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior | CommandBehavior.SchemaOnly);
        reader.Read();
        Assert.That(reader.GetFieldType(0), Is.SameAs(typeof(int)));
    }

    [Test]
    public async Task GetPostgresType()
    {
        using var conn = await OpenConnectionAsync();
        PostgresType intType;
        using (var cmd = new NpgsqlCommand(@"SELECT 1::INTEGER AS some_column", conn))
        using (var reader = await cmd.ExecuteReaderAsync(Behavior))
        {
            reader.Read();
            intType = (PostgresBaseType)reader.GetPostgresType(0);
            Assert.That(intType.Namespace, Is.EqualTo("pg_catalog"));
            Assert.That(intType.Name, Is.EqualTo("integer"));
            Assert.That(intType.FullName, Is.EqualTo("pg_catalog.integer"));
            Assert.That(intType.DisplayName, Is.EqualTo("integer"));
            Assert.That(intType.InternalName, Is.EqualTo("int4"));
        }

        using (var cmd = new NpgsqlCommand(@"SELECT '{1}'::INTEGER[] AS some_column", conn))
        using (var reader = await cmd.ExecuteReaderAsync(Behavior))
        {
            reader.Read();
            var intArrayType = (PostgresArrayType)reader.GetPostgresType(0);
            Assert.That(intArrayType.Name, Is.EqualTo("integer[]"));
            Assert.That(intArrayType.Element, Is.SameAs(intType));
            Assert.That(intArrayType.DisplayName, Is.EqualTo("integer[]"));
            Assert.That(intArrayType.InternalName, Is.EqualTo("_int4"));
            Assert.That(intType.Array, Is.SameAs(intArrayType));
        }
    }

    /// <seealso cref="ReaderNewSchemaTests.DataTypeName"/>
    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/787")]
    [TestCase("integer")]
    [TestCase("real")]
    [TestCase("integer[]")]
    [TestCase("character varying(10)")]
    [TestCase("character varying")]
    [TestCase("character varying(10)[]")]
    [TestCase("character(10)")]
    [TestCase("character")]
    [TestCase("character(1)", "character")]
    [TestCase("numeric(1000, 2)")]
    [TestCase("numeric(1000)")]
    [TestCase("numeric")]
    [TestCase("timestamp without time zone")]
    [TestCase("timestamp(2) without time zone")]
    [TestCase("timestamp(2) with time zone")]
    [TestCase("time without time zone")]
    [TestCase("time(2) without time zone")]
    [TestCase("time(2) with time zone")]
    [TestCase("interval")]
    [TestCase("interval(2)")]
    [TestCase("bit", "bit(1)")]
    [TestCase("bit(3)")]
    [TestCase("bit varying")]
    [TestCase("bit varying(3)")]
    public async Task GetDataTypeName(string typeName, string? normalizedName = null)
    {
        if (normalizedName == null)
            normalizedName = typeName;
        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand($"SELECT NULL::{typeName} AS some_column", conn);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Read();
        Assert.That(reader.GetDataTypeName(0), Is.EqualTo(normalizedName));
    }

    [Test]
    public async Task GetDataTypeName_enum()
    {
        await using var dataSource = CreateDataSource(csb => csb.MaxPoolSize = 1);
        await using var conn = await dataSource.OpenConnectionAsync();
        var typeName = await GetTempTypeName(conn);
        await conn.ExecuteNonQueryAsync($"CREATE TYPE {typeName} AS ENUM ('one')");
        conn.ReloadTypes();
        await using var cmd = new NpgsqlCommand($"SELECT 'one'::{typeName}", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);
        await reader.ReadAsync();
        Assert.That(reader.GetDataTypeName(0), Is.EqualTo($"public.{typeName}"));
    }

    [Test]
    public async Task GetDataTypeName_domain()
    {
        await using var dataSource = CreateDataSource(csb => csb.MaxPoolSize = 1);
        await using var conn = await dataSource.OpenConnectionAsync();
        var typeName = await GetTempTypeName(conn);
        await conn.ExecuteNonQueryAsync($"CREATE DOMAIN {typeName} AS VARCHAR(10)");
        conn.ReloadTypes();
        await using var cmd = new NpgsqlCommand($"SELECT 'one'::{typeName}", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);
        await reader.ReadAsync();
        // In the RowDescription, PostgreSQL sends the type OID of the underlying type and not of the domain.
        Assert.That(reader.GetDataTypeName(0), Is.EqualTo("character varying(10)"));
    }

    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/794")]
    public async Task GetDataTypeNameTypes_unknown()
    {
        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand(@"SELECT 1::INTEGER AS some_column", conn);
        cmd.AllResultTypesAreUnknown = true;
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Read();
        Assert.That(reader.GetDataTypeName(0), Is.EqualTo("integer"));
    }

    [Test]
    [IssueLink("https://github.com/npgsql/npgsql/issues/791")]
    [IssueLink("https://github.com/npgsql/npgsql/issues/794")]
    public async Task GetDataTypeOID()
    {
        using var conn = await OpenConnectionAsync();
        var int4OID = await conn.ExecuteScalarAsync("SELECT oid FROM pg_type WHERE typname = 'int4'");
        using (var cmd = new NpgsqlCommand(@"SELECT 1::INT4 AS some_column", conn))
        using (var reader = await cmd.ExecuteReaderAsync(Behavior))
        {
            reader.Read();
            Assert.That(reader.GetDataTypeOID(0), Is.EqualTo(int4OID));
        }
        using (var cmd = new NpgsqlCommand(@"SELECT 1::INT4 AS some_column", conn))
        {
            cmd.AllResultTypesAreUnknown = true;
            using (var reader = await cmd.ExecuteReaderAsync(Behavior))
            {
                reader.Read();
                Assert.That(reader.GetDataTypeOID(0), Is.EqualTo(int4OID));
            }
        }
    }

    [Test]
    public async Task GetName()
    {
        using var conn = await OpenConnectionAsync();
        using var command = new NpgsqlCommand(@"SELECT 1 AS some_column", conn);
        using var dr = await command.ExecuteReaderAsync(Behavior);
        dr.Read();
        Assert.That(dr.GetName(0), Is.EqualTo("some_column"));
    }

    [Test]
    public async Task GetFieldValue_as_object()
    {
        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand("SELECT 'foo'::TEXT", conn);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Read();
        Assert.That(reader.GetFieldValue<object>(0), Is.EqualTo("foo"));
    }

    [Test]
    public async Task GetValues()
    {
        using var conn = await OpenConnectionAsync();
        using var command = new NpgsqlCommand(@"SELECT 'hello', 1, '2014-01-01'::DATE", conn);
        using (var dr = await command.ExecuteReaderAsync(Behavior))
        {
            dr.Read();
            var values = new object[4];
            Assert.That(dr.GetValues(values), Is.EqualTo(3));
            Assert.That(values, Is.EqualTo(new object?[] { "hello", 1, new DateOnly(2014, 1, 1), null }));
        }
        using (var dr = await command.ExecuteReaderAsync(Behavior))
        {
            dr.Read();
            var values = new object[2];
            Assert.That(dr.GetValues(values), Is.EqualTo(2));
            Assert.That(values, Is.EqualTo(new object[] { "hello", 1 }));
        }
    }

    [Test]
    public async Task ExecuteReader_getting_empty_resultset_with_output_parameter()
    {
        using var conn = await OpenConnectionAsync();
        var table = await CreateTempTable(conn, "name TEXT");
        var command = new NpgsqlCommand($"SELECT * FROM {table} WHERE name = NULL;", conn);
        var param = new NpgsqlParameter("some_param", NpgsqlDbType.Varchar);
        param.Direction = ParameterDirection.Output;
        command.Parameters.Add(param);
        using var dr = await command.ExecuteReaderAsync(Behavior);
        Assert.That(dr.NextResult(), Is.False);
    }

    [Test]
    public async Task Get_value_from_empty_resultset()
    {
        using var conn = await OpenConnectionAsync();
        var table = await CreateTempTable(conn, "name TEXT");
        using var command = new NpgsqlCommand($"SELECT * FROM {table} WHERE name = :value;", conn);
        const string test = "Text single quote";
        var param = new NpgsqlParameter();
        param.ParameterName = "value";
        param.DbType = DbType.String;
        //param.NpgsqlDbType = NpgsqlDbType.Text;
        param.Size = test.Length;
        param.Value = test;
        command.Parameters.Add(param);

        using var dr = await command.ExecuteReaderAsync(Behavior);
        dr.Read();
        // This line should throw the invalid operation exception as the datareader will
        // have an empty resultset.
        Assert.That(() => Console.WriteLine(dr.IsDBNull(1)),
            Throws.Exception.TypeOf<InvalidOperationException>());
    }

    [Test]
    public async Task Read_past_reader_end()
    {
        using var conn = await OpenConnectionAsync();
        var command = new NpgsqlCommand("SELECT 1", conn);
        using var dr = await command.ExecuteReaderAsync(Behavior);
        while (dr.Read()) {}
        Assert.That(() => dr[0], Throws.Exception.TypeOf<InvalidOperationException>());
    }

    [Test]
    public async Task Reader_dispose_state_does_not_leak()
    {
        if (Behavior != CommandBehavior.Default)
            return;

        var startReaderClosedTcs = new TaskCompletionSource<object>(TaskCreationOptions.RunContinuationsAsynchronously);
        var continueReaderClosedTcs = new TaskCompletionSource<object>(TaskCreationOptions.RunContinuationsAsynchronously);

        await using var dataSource = CreateDataSource();
        await using var conn1 = await dataSource.OpenConnectionAsync();
        var connID = conn1.Connector!.Id;
        var readerCloseTask = Task.Run(async () =>
        {
            using var cmd = conn1.CreateCommand();
            cmd.CommandText = "SELECT 1";
            await using var reader = await cmd.ExecuteReaderAsync(CommandBehavior.CloseConnection);
            reader.ReaderClosed += (s, e) =>
            {
                startReaderClosedTcs.SetResult(new());
                continueReaderClosedTcs.Task.GetAwaiter().GetResult();
            };
        });

        await startReaderClosedTcs.Task;
        await using var conn2 = await dataSource.OpenConnectionAsync();
        Assert.That(conn2.Connector!.Id, Is.EqualTo(connID));
        using var cmd = conn2.CreateCommand();
        cmd.CommandText = "SELECT 1";
        await using var reader = await cmd.ExecuteReaderAsync();
        Assert.That(reader.State, Is.EqualTo(ReaderState.BeforeResult));
        continueReaderClosedTcs.SetResult(new());
        await readerCloseTask;
        Assert.That(reader.State, Is.EqualTo(ReaderState.BeforeResult));
    }

    [Test]
    public async Task SingleResult()
    {
        await using var conn = await OpenConnectionAsync();
        await using var command = new NpgsqlCommand(@"SELECT 1; SELECT 2", conn);
        var reader = await command.ExecuteReaderAsync(CommandBehavior.SingleResult | Behavior);
        Assert.That(reader.Read(), Is.True);
        Assert.That(reader.GetInt32(0), Is.EqualTo(1));
        Assert.That(reader.NextResult(), Is.False);
    }

    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/400")]
    public async Task Exception_thrown_from_ExecuteReaderAsync([Values(PrepareOrNot.Prepared, PrepareOrNot.NotPrepared)] PrepareOrNot prepare)
    {
        using var conn = await OpenConnectionAsync();
        var function = await GetTempFunctionName(conn);

        await conn.ExecuteNonQueryAsync($@"
CREATE OR REPLACE FUNCTION {function}() RETURNS VOID AS
   'BEGIN RAISE EXCEPTION ''testexception'' USING ERRCODE = ''12345''; END;'
LANGUAGE 'plpgsql';
                ");

        using var cmd = new NpgsqlCommand($"SELECT {function}()", conn);
        if (prepare == PrepareOrNot.Prepared)
            cmd.Prepare();
        Assert.That(async () => await cmd.ExecuteReaderAsync(Behavior), Throws.Exception.TypeOf<PostgresException>());
    }

    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/1032")]
    public async Task Exception_thrown_from_NextResult([Values(PrepareOrNot.Prepared, PrepareOrNot.NotPrepared)] PrepareOrNot prepare)
    {
        using var conn = await OpenConnectionAsync();
        var function = await GetTempFunctionName(conn);

        await conn.ExecuteNonQueryAsync($@"
CREATE OR REPLACE FUNCTION {function}() RETURNS VOID AS
   'BEGIN RAISE EXCEPTION ''testexception'' USING ERRCODE = ''12345''; END;'
LANGUAGE 'plpgsql';
                ");

        using var cmd = new NpgsqlCommand($"SELECT 1; SELECT {function}()", conn);
        if (prepare == PrepareOrNot.Prepared)
            cmd.Prepare();
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        Assert.That(() => reader.NextResult(), Throws.Exception.TypeOf<PostgresException>());
    }

    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/967")]
    public async Task NpgsqlException_references_BatchCommand_with_single_command([Values] bool includeFailedBatchedCommand)
    {
        await using var dataSource = CreateDataSource(x => x.IncludeFailedBatchedCommand = includeFailedBatchedCommand);
        await using var conn = await dataSource.OpenConnectionAsync();
        var function = await GetTempFunctionName(conn);

        await conn.ExecuteNonQueryAsync($@"
CREATE OR REPLACE FUNCTION {function}() RETURNS VOID AS
   'BEGIN RAISE EXCEPTION ''testexception'' USING ERRCODE = ''12345''; END;'
LANGUAGE 'plpgsql'");

        // We use NpgsqlConnection.CreateCommand to test that the command isn't recycled when referenced in an exception
        var cmd = conn.CreateCommand();
        cmd.CommandText = $"SELECT {function}()";

        var exception = Assert.ThrowsAsync<PostgresException>(() => cmd.ExecuteReaderAsync(Behavior))!;
        if (includeFailedBatchedCommand)
            Assert.That(exception.BatchCommand, Is.SameAs(cmd.InternalBatchCommands[0]));
        else
            Assert.That(exception.BatchCommand, Is.Null);

        // Make sure the command isn't recycled by the connection when it's disposed - this is important since internal command
        // resources are referenced by the exception above, which is very likely to escape the using statement of the command.
        cmd.Dispose();
        var cmd2 = conn.CreateCommand();
        Assert.That(cmd, Is.Not.SameAs(cmd2));
    }

    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/967")]
    public async Task NpgsqlException_references_BatchCommand_with_multiple_commands([Values] bool includeFailedBatchedCommand)
    {
        await using var dataSource = CreateDataSource(x => x.IncludeFailedBatchedCommand = includeFailedBatchedCommand);
        await using var conn = await dataSource.OpenConnectionAsync();
        var function = await GetTempFunctionName(conn);

        await conn.ExecuteNonQueryAsync($@"
CREATE OR REPLACE FUNCTION {function}() RETURNS VOID AS
   'BEGIN RAISE EXCEPTION ''testexception'' USING ERRCODE = ''12345''; END;'
LANGUAGE 'plpgsql'");

        // We use NpgsqlConnection.CreateCommand to test that the command isn't recycled when referenced in an exception
        var cmd = conn.CreateCommand();
        cmd.CommandText = $"SELECT 1; {function}()";

        await using (var reader = await cmd.ExecuteReaderAsync(Behavior))
        {
            var exception = Assert.ThrowsAsync<PostgresException>(() => reader.NextResultAsync())!;
            if (includeFailedBatchedCommand)
                Assert.That(exception.BatchCommand, Is.SameAs(cmd.InternalBatchCommands[1]));
            else
                Assert.That(exception.BatchCommand, Is.Null);
        }

        // Make sure the command isn't recycled by the connection when it's disposed - this is important since internal command
        // resources are referenced by the exception above, which is very likely to escape the using statement of the command.
        cmd.Dispose();
        var cmd2 = conn.CreateCommand();
        Assert.That(cmd, Is.Not.SameAs(cmd2));
    }

    #region SchemaOnly

    [Test]
    public async Task SchemaOnly_returns_no_data()
    {
        await using var conn = await OpenConnectionAsync();
        await using var cmd = new NpgsqlCommand("SELECT 1", conn);
        await using var reader = await cmd.ExecuteReaderAsync(CommandBehavior.SchemaOnly);
        Assert.That(reader.Read(), Is.False);
    }

    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/2827")]
    public async Task SchemaOnly_next_result_beyond_end()
    {
        using var conn = await OpenConnectionAsync();
        var table = await CreateTempTable(conn, "id INT");

        using var cmd = new NpgsqlCommand($"SELECT * FROM {table}", conn);
        using var reader = await cmd.ExecuteReaderAsync(CommandBehavior.SchemaOnly);
        Assert.That(reader.NextResult(), Is.False);
        Assert.That(reader.NextResult(), Is.False);
    }

    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/4124")]
    public async Task SchemaOnly_GetDataTypeName_with_unsupported_type()
    {
        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand(@"select aggfnoid from pg_aggregate", conn);
        using var reader = await cmd.ExecuteReaderAsync(CommandBehavior.SchemaOnly);

        Assert.That(reader.GetDataTypeName(0), Is.EqualTo("regproc"));
    }

    #endregion SchemaOnly

    #region GetOrdinal

    [Test]
    public async Task GetOrdinal()
    {
        using var conn = await OpenConnectionAsync();
        using var command = new NpgsqlCommand(@"SELECT 0, 1 AS some_column WHERE 1=0", conn);
        using var reader = await command.ExecuteReaderAsync(Behavior);
        Assert.That(reader.GetOrdinal("some_column"), Is.EqualTo(1));
        Assert.That(() => reader.GetOrdinal("doesn't_exist"), Throws.Exception.TypeOf<IndexOutOfRangeException>());
    }

    [Test]
    public async Task GetOrdinal_case_insensitive()
    {
        using var conn = await OpenConnectionAsync();
        using var command = new NpgsqlCommand("select 123 as FIELD1", conn);
        using var reader = await command.ExecuteReaderAsync(Behavior);
        reader.Read();
        Assert.That(reader.GetOrdinal("fieLd1"), Is.EqualTo(0));
    }

    [Test]
    public async Task GetOrdinal_kana_insensitive()
    {
        using var conn = await OpenConnectionAsync();
        using var command = new NpgsqlCommand("select 123 as ｦｧｨｩｪｫｬ", conn);
        using var reader = await command.ExecuteReaderAsync(Behavior);
        reader.Read();
        Assert.That(reader["ヲァィゥェォャ"], Is.EqualTo(123));
    }

    #endregion GetOrdinal

    [Test]
    public async Task Field_index_does_not_exist()
    {
        using var conn = await OpenConnectionAsync();
        using var command = new NpgsqlCommand("SELECT 1", conn);
        using var dr = await command.ExecuteReaderAsync(Behavior);
        dr.Read();

        Assert.That(() => dr[1], AssertExpectedException());
        Assert.That(() => dr.GetValue(2), AssertExpectedException());
        Assert.That(() => dr.GetFieldValue<object>(3), AssertExpectedException());

        static IResolveConstraint AssertExpectedException()
            => Throws.Exception.TypeOf<IndexOutOfRangeException>().With.Message.StartsWith("Ordinal is out of range");
    }

    [Test, Description("Performs some operations while a reader is still open and checks for exceptions")]
    public async Task Reader_is_still_open()
    {
        await using var conn = await OpenConnectionAsync();
        // We might get the connection, on which the second command was already prepared, so prepare wouldn't start the UserAction
        conn.UnprepareAll();
        using var cmd1 = new NpgsqlCommand("SELECT 1", conn);
        await using var reader1 = await cmd1.ExecuteReaderAsync(Behavior);
        Assert.That(() => conn.ExecuteNonQuery("SELECT 1"), Throws.Exception.TypeOf<NpgsqlOperationInProgressException>());
        Assert.That(async () => await conn.ExecuteScalarAsync("SELECT 1"), Throws.Exception.TypeOf<NpgsqlOperationInProgressException>());

        using var cmd2 = new NpgsqlCommand("SELECT 2", conn);
        Assert.That(() => cmd2.ExecuteReader(Behavior), Throws.Exception.TypeOf<NpgsqlOperationInProgressException>());
        Assert.That(() => cmd2.Prepare(), Throws.Exception.TypeOf<NpgsqlOperationInProgressException>());
    }

    [Test]
    public async Task Cleans_up_ok_with_dispose_calls([Values(PrepareOrNot.Prepared, PrepareOrNot.NotPrepared)] PrepareOrNot prepare)
    {
        using var conn = await OpenConnectionAsync();
        using var command = new NpgsqlCommand("SELECT 1", conn);
        using var dr = await command.ExecuteReaderAsync(Behavior);
        dr.Read();
        dr.Close();

        using var upd = conn.CreateCommand();
        upd.CommandText = "SELECT 1";
        if (prepare == PrepareOrNot.Prepared)
            upd.Prepare();
    }

    [Test]
    public async Task Null()
    {
        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand("SELECT @p1, @p2::TEXT", conn);
        cmd.Parameters.Add(new NpgsqlParameter("p1", DbType.String) { Value = DBNull.Value });
        cmd.Parameters.Add(new NpgsqlParameter { ParameterName = "p2", Value = DBNull.Value });

        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Read();

        for (var i = 0; i < cmd.Parameters.Count; i++)
        {
            Assert.That(reader.IsDBNull(i), Is.True);
            Assert.That(reader.IsDBNullAsync(i).Result, Is.True);
            Assert.That(reader.GetValue(i), Is.EqualTo(DBNull.Value));
            Assert.That(reader.GetFieldValue<object>(i), Is.EqualTo(DBNull.Value));
            Assert.That(reader.GetProviderSpecificValue(i), Is.EqualTo(DBNull.Value));
            Assert.That(() => reader.GetString(i), Throws.Exception.TypeOf<InvalidCastException>());
            Assert.That(() => reader.GetStream(i), Throws.Exception.TypeOf<InvalidCastException>());
        }
    }

    [Test]
    [IssueLink("https://github.com/npgsql/npgsql/issues/742")]
    [IssueLink("https://github.com/npgsql/npgsql/issues/800")]
    [IssueLink("https://github.com/npgsql/npgsql/issues/1234")]
    [IssueLink("https://github.com/npgsql/npgsql/issues/1898")]
    public async Task HasRows([Values(PrepareOrNot.NotPrepared, PrepareOrNot.Prepared)] PrepareOrNot prepare)
    {
        using var conn = await OpenConnectionAsync();
        var table = await CreateTempTable(conn, "name TEXT");

        var command = new NpgsqlCommand($"SELECT 1; SELECT * FROM {table} WHERE name='does_not_exist'", conn);
        if (prepare == PrepareOrNot.Prepared)
            command.Prepare();
        using (var reader = await command.ExecuteReaderAsync(Behavior))
        {
            Assert.That(reader.HasRows, Is.True);
            Assert.That(reader.HasRows, Is.True);
            Assert.That(reader.Read(), Is.True);
            Assert.That(reader.HasRows, Is.True);
            Assert.That(reader.Read(), Is.False);
            Assert.That(reader.HasRows, Is.True);
            await reader.NextResultAsync();
            Assert.That(reader.HasRows, Is.False);
        }

        command.CommandText = $"SELECT * FROM {table}";
        if (prepare == PrepareOrNot.Prepared)
            command.Prepare();
        using (var reader = await command.ExecuteReaderAsync(Behavior))
        {
            reader.Read();
            Assert.That(reader.HasRows, Is.False);
        }

        command.CommandText = "SELECT 1";
        if (prepare == PrepareOrNot.Prepared)
            command.Prepare();
        using (var reader = await command.ExecuteReaderAsync(Behavior))
        {
            reader.Read();
            reader.Close();
            Assert.That(() => reader.HasRows, Throws.Exception.TypeOf<InvalidOperationException>());
        }

        command.CommandText = $"INSERT INTO {table} (name) VALUES ('foo'); SELECT * FROM {table}";
        if (prepare == PrepareOrNot.Prepared)
            command.Prepare();
        using (var reader = await command.ExecuteReaderAsync(Behavior))
        {
            Assert.That(reader.HasRows, Is.True);
            reader.Read();
            Assert.That(reader.GetString(0), Is.EqualTo("foo"));
        }

        Assert.That(await conn.ExecuteScalarAsync("SELECT 1"), Is.EqualTo(1));
    }

    [Test]
    public async Task HasRows_without_resultset()
    {
        using var conn = await OpenConnectionAsync();
        var table = await CreateTempTable(conn, "name TEXT");
        using var command = new NpgsqlCommand($"DELETE FROM {table} WHERE name = 'unknown'", conn);
        using var reader = await command.ExecuteReaderAsync(Behavior);
        Assert.That(reader.HasRows, Is.False);
    }

    [Test]
    public async Task Interval_as_TimeSpan()
    {
        using var conn = await OpenConnectionAsync();
        using var command = new NpgsqlCommand("SELECT CAST('1 hour' AS interval) AS dauer", conn);
        using var dr = await command.ExecuteReaderAsync(Behavior);
        Assert.That(dr.HasRows);
        Assert.That(dr.Read());
        Assert.That(dr.HasRows);
        var ts = dr.GetTimeSpan(0);
    }

    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/5439")]
    public async Task SequentialBufferedSeek()
    {
        await using var conn = await OpenConnectionAsync();
        using var cmd = conn.CreateCommand();
        cmd.CommandText = """select v.i, jsonb_build_object(), current_timestamp + make_interval(0, 0, 0, 0, 0, 0, v.i), null::jsonb, '{"value": 42}'::jsonb from generate_series(1, 1000) as v(i)""";
        var rdr = await cmd.ExecuteReaderAsync(Behavior);
        while (await rdr.ReadAsync()) {
            var v1 = rdr[0];
            var v2 = rdr[1];
            //_ = rdr[2]; // uncomment line for successful execution
            var v3 = rdr[3];
            var v4 = rdr[4];
        }
    }

    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/5430")]
    public async Task SequentialBufferedSeekLong()
    {
        await using var conn = await OpenConnectionAsync();
        using var cmd = conn.CreateCommand();
        cmd.CommandText = """select v.i, repeat('1', 10), repeat('2', 10), repeat('3', 10), repeat('4', 10), 1, 2 from generate_series(1, 1000) as v(i)""";
        var rdr = await cmd.ExecuteReaderAsync(Behavior);
        while (await rdr.ReadAsync())
        {
            _ = rdr[0];
            _ = rdr[1];
            //_ = rdr[2];
            //_ = rdr[3];
            //_ = rdr[4];
            //_ = rdr[5]; // uncomment lines for successful execution
            _ = rdr[6];
        }
    }

    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/5430")]
    public async Task SequentialBufferedSeekReread()
    {
        await using var conn = await OpenConnectionAsync();
        using var cmd = conn.CreateCommand();
        cmd.CommandText = """select v.i, repeat('1', 10), repeat('2', 10), repeat('3', 10), repeat('4', 10), 1, NULL from generate_series(1, 1000) as v(i)""";
        var rdr = await cmd.ExecuteReaderAsync(Behavior);
        while (await rdr.ReadAsync())
        {
            _ = rdr[0];
            _ = rdr[1];
            //_ = rdr[2];
            //_ = rdr[3];
            //_ = rdr[4];
            //_ = rdr[5]; // uncomment lines for successful execution
            _ = rdr.IsDBNull(6);
            _ = rdr[6];
            Assert.That(rdr.IsDBNull(6));
        }
    }

    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/5484")]
    public async Task GetFieldValueAsync_AsyncRead()
    {
        if (!IsSequential)
            return;

        await using var postmasterMock = PgPostmasterMock.Start(ConnectionString);
        await using var dataSource = CreateDataSource(postmasterMock.ConnectionString);
        await using var conn = await dataSource.OpenConnectionAsync();

        var expected = new byte[10000];
        expected.AsSpan().Fill(1);

        var pgMock = await postmasterMock.WaitForServerConnection();
        await pgMock
            .WriteParseComplete()
            .WriteBindComplete()
            .WriteRowDescription(new FieldDescription(ByteaOid))
            .WriteDataRowWithFlush(expected);

        using var cmd = new NpgsqlCommand("irrelevant", conn);
        var reader = await cmd.ExecuteReaderAsync(Behavior);
        while (await reader.ReadAsync())
        {
            var task = reader.GetFieldValueAsync<object>(0);
            await pgMock
                .WriteCommandComplete()
                .WriteReadyForQuery()
                .FlushAsync();
            Assert.That(await task, Is.EqualTo(expected));
        }
    }

    [Test]
    public async Task Close_connection_in_middle_of_row()
    {
        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand("SELECT 1, 2", conn);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Read();
    }

    [Test, IssueLink("https://github.com/npgsql/npgsql/pull/1266")]
    [Description("NextResult was throwing an ArgumentOutOfRangeException when trying to determine the statement to associate with the PostgresException")]
    public async Task Reader_next_result_exception_handling()
    {
        using var conn = await OpenConnectionAsync();
        var table1 = await GetTempTableName(conn);
        var table2 = await GetTempTableName(conn);
        var function = await GetTempFunctionName(conn);

        var initializeTablesSql = $@"
CREATE TABLE {table1} (value int NOT NULL);
CREATE TABLE {table2} (value int UNIQUE);
ALTER TABLE ONLY {table1} ADD CONSTRAINT {table1}_{table2}_fk FOREIGN KEY (value) REFERENCES {table2}(value) DEFERRABLE INITIALLY DEFERRED;
CREATE OR REPLACE FUNCTION {function}(_value int) RETURNS int AS $BODY$
BEGIN
    INSERT INTO {table1}(value) VALUES(_value);
    RETURN _value;
END;
$BODY$
LANGUAGE plpgsql VOLATILE";

        await conn.ExecuteNonQueryAsync(initializeTablesSql);
        using var cmd = new NpgsqlCommand($"SELECT {function}(1)", conn);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        Assert.That(() => reader.NextResult(),
            Throws.Exception.TypeOf<PostgresException>()
                .With.Property(nameof(PostgresException.SqlState)).EqualTo(PostgresErrorCodes.ForeignKeyViolation));
    }

    [Test]
    public async Task Invalid_cast()
    {
        using var conn = await OpenConnectionAsync();
        // Chunking type handler
        using (var cmd = new NpgsqlCommand("SELECT 'foo'", conn))
        using (var reader = await cmd.ExecuteReaderAsync(Behavior))
        {
            reader.Read();
            Assert.That(() => reader.GetInt32(0), Throws.Exception.TypeOf<InvalidCastException>());
        }
        // Simple type handler
        using (var cmd = new NpgsqlCommand("SELECT 1", conn))
        using (var reader = await cmd.ExecuteReaderAsync(Behavior))
        {
            reader.Read();
            Assert.That(() => reader.GetDateTime(0), Throws.Exception.TypeOf<InvalidCastException>());
        }
        Assert.That(await conn.ExecuteScalarAsync("SELECT 1"), Is.EqualTo(1));
    }

    [Test, Description("Reads a lot of rows to make sure the long unoptimized path for Read() works")]
    public async Task Many_reads()
    {
        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand($"SELECT generate_series(1, {conn.Settings.ReadBufferSize})", conn);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        for (var i = 1; i <= conn.Settings.ReadBufferSize; i++)
        {
            Assert.That(reader.Read(), Is.True);
            Assert.That(reader.GetInt32(0), Is.EqualTo(i));
        }
        Assert.That(reader.Read(), Is.False);
    }

    [Test]
    public async Task Nullable_scalar()
    {
        // We read the same column multiple times
        if (IsSequential)
            return;

        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand("SELECT @p1, @p2", conn);
        var p1 = new NpgsqlParameter { ParameterName = "p1", Value = DBNull.Value, NpgsqlDbType = NpgsqlDbType.Smallint };
        var p2 = new NpgsqlParameter { ParameterName = "p2", Value = (short)8 };
        Assert.That(p2.NpgsqlDbType, Is.EqualTo(NpgsqlDbType.Smallint));
        Assert.That(p2.DbType, Is.EqualTo(DbType.Int16));
        cmd.Parameters.Add(p1);
        cmd.Parameters.Add(p2);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Read();

        for (var i = 0; i < cmd.Parameters.Count; i++)
        {
            Assert.That(reader.GetFieldType(i), Is.EqualTo(typeof(short)));
            Assert.That(reader.GetDataTypeName(i), Is.EqualTo("smallint"));
        }

        Assert.That(() => reader.GetFieldValue<object>(0), Is.EqualTo(DBNull.Value));
        Assert.That(() => reader.GetFieldValue<int>(0), Throws.TypeOf<InvalidCastException>());
        Assert.That(() => reader.GetFieldValue<int?>(0), Throws.Nothing);
        Assert.That(reader.GetFieldValue<int?>(0), Is.Null);

        Assert.That(() => reader.GetFieldValue<object>(1), Throws.Nothing);
        Assert.That(() => reader.GetFieldValue<int>(1), Throws.Nothing);
        Assert.That(() => reader.GetFieldValue<int?>(1), Throws.Nothing);
        Assert.That(reader.GetFieldValue<object>(1), Is.EqualTo(8));
        Assert.That(reader.GetFieldValue<int>(1), Is.EqualTo(8));
        Assert.That(reader.GetFieldValue<int?>(1), Is.EqualTo(8));
    }

    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/2913")]
    public async Task Bug2913_reading_previous_query_messages()
    {
        var firstMrs = new ManualResetEventSlim(false);
        var secondMrs = new ManualResetEventSlim(false);

        var secondQuery = Task.Run(async () =>
        {
            firstMrs.Wait();
            await using var secondConn = await OpenConnectionAsync();
            using var secondCmd = new NpgsqlCommand(@"SELECT 1; SELECT 2;", secondConn);
            await using var secondReader = await secondCmd.ExecuteReaderAsync(Behavior | CommandBehavior.CloseConnection);

            // Check, that StatementIndex is equals to default value
            Assert.That(secondReader.StatementIndex, Is.EqualTo(0));
            secondMrs.Wait();
            // Check, that the first query didn't change StatementIndex
            Assert.That(secondReader.StatementIndex, Is.EqualTo(0));
        });

        await using (var firstConn = await OpenConnectionAsync())
        {
            // Executing a query, which fails with NpgsqlException on reader disposing, as NotExistingTable doesn't exist
            using var firstCmd = new NpgsqlCommand(@"SELECT 1; SELECT * FROM NotExistingTable;", firstConn);
            await using var firstReader = await firstCmd.ExecuteReaderAsync(Behavior | CommandBehavior.CloseConnection);

            Assert.That(firstReader.StatementIndex, Is.EqualTo(0));

            firstReader.ReaderClosed += (s, e) =>
            {
                // Starting a second query, which in case of a bug uses firstConn
                firstMrs.Set();
                // Waiting for the second query to start executing
                Thread.Sleep(100);
                // After waiting, reader is free to reset prepared statements, which also increments StatementIndex
            };

            Assert.ThrowsAsync<PostgresException>(firstReader.NextResultAsync);

            secondMrs.Set();
        }

        await secondQuery;

        // If we're here and a bug is still not fixed, we fail while executing reader, as we're reading skipped messages for the second query
        await using var thirdConn = OpenConnection();
        using var thirdCmd = new NpgsqlCommand(@"SELECT 1; SELECT 2;", thirdConn);
        await using var thirdReader = await thirdCmd.ExecuteReaderAsync(Behavior | CommandBehavior.CloseConnection);
    }

    [Test]
    [IssueLink("https://github.com/npgsql/npgsql/issues/2913")]
    [IssueLink("https://github.com/npgsql/npgsql/issues/3289")]
    public async Task Reader_close_and_dispose()
    {
        await using var conn = await OpenConnectionAsync();
        using var cmd1 = conn.CreateCommand();
        cmd1.CommandText = "SELECT 1";

        var reader1 = await cmd1.ExecuteReaderAsync(Behavior | CommandBehavior.CloseConnection);
        await reader1.CloseAsync();

        await conn.OpenAsync();
        cmd1.Connection = conn;
        var reader2 = await cmd1.ExecuteReaderAsync(Behavior | CommandBehavior.CloseConnection);
        Assert.That(reader1, Is.Not.SameAs(reader2));
        Assert.That(reader2.State, Is.EqualTo(ReaderState.BeforeResult));

        await reader1.DisposeAsync();

        Assert.That(reader2.State, Is.EqualTo(ReaderState.BeforeResult));
    }

    [Test]
    [IssueLink("https://github.com/npgsql/npgsql/issues/2964")]
    public async Task Bug2964_connection_close_and_reader_dispose()
    {
        await using var conn = await OpenConnectionAsync();
        using var cmd1 = conn.CreateCommand();
        cmd1.CommandText = "SELECT 1";

        var reader1 = await cmd1.ExecuteReaderAsync(Behavior);
        await conn.CloseAsync();
        await conn.OpenAsync();

        var reader2 = await cmd1.ExecuteReaderAsync(Behavior);
        Assert.That(reader1, Is.Not.SameAs(reader2));
        Assert.That(reader2.State, Is.EqualTo(ReaderState.BeforeResult));

        await reader1.DisposeAsync();

        Assert.That(reader2.State, Is.EqualTo(ReaderState.BeforeResult));
    }

    [Test]
    public async Task Reader_reuse_on_dispose()
    {
        await using var conn = await OpenConnectionAsync();
        await using var tx = await conn.BeginTransactionAsync();
        using var cmd = conn.CreateCommand();
        cmd.CommandText = "SELECT 1";

        var reader1 = await cmd.ExecuteReaderAsync(Behavior);
        await reader1.ReadAsync();
        await reader1.DisposeAsync();

        var reader2 = await cmd.ExecuteReaderAsync(Behavior);
        Assert.That(reader1, Is.SameAs(reader2));
        await reader2.DisposeAsync();
    }

    [Test]
    public async Task Unbound_reader_reuse()
    {
        await using var dataSource = CreateDataSource(csb =>
        {
            csb.MinPoolSize = 1;
            csb.MaxPoolSize = 1;
        });
        await using var conn1 = await dataSource.OpenConnectionAsync();
        using var cmd1 = conn1.CreateCommand();
        cmd1.CommandText = "SELECT 1";
        var reader1 = await cmd1.ExecuteReaderAsync(Behavior);
        await using (var __ = reader1)
        {
            Assert.That(async () => await reader1.ReadAsync(), Is.EqualTo(true));
            Assert.That(() => reader1.GetInt32(0), Is.EqualTo(1));

            await reader1.CloseAsync();
            await conn1.CloseAsync();
        }

        await using var conn2 = await dataSource.OpenConnectionAsync();
        using var cmd2 = conn2.CreateCommand();
        cmd2.CommandText = "SELECT 2";
        var reader2 = await cmd2.ExecuteReaderAsync(Behavior);
        await using (var __ = reader2)
        {
            Assert.That(async () => await reader2.ReadAsync(), Is.EqualTo(true));
            Assert.That(() => reader2.GetInt32(0), Is.EqualTo(2));
            Assert.That(reader1, Is.Not.SameAs(reader2));

            await reader2.CloseAsync();
            await conn2.CloseAsync();
        }

        await using var conn3 = await dataSource.OpenConnectionAsync();
        using var cmd3 = conn3.CreateCommand();
        cmd3.CommandText = "SELECT 3";
        var reader3 = await cmd3.ExecuteReaderAsync(Behavior);
        await using (var __ = reader3)
        {
            Assert.That(async () => await reader3.ReadAsync(), Is.EqualTo(true));
            Assert.That(() => reader3.GetInt32(0), Is.EqualTo(3));
            Assert.That(reader1, Is.SameAs(reader3));

            await reader3.CloseAsync();
            await conn3.CloseAsync();
        }
    }

    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/3772")]
    public async Task Bug3772()
    {
        if (!IsSequential)
            return;

        await using var postmasterMock = PgPostmasterMock.Start(ConnectionString);
        await using var dataSource = CreateDataSource(postmasterMock.ConnectionString);
        await using var conn = await dataSource.OpenConnectionAsync();

        var pgMock = await postmasterMock.WaitForServerConnection();
        pgMock
            .WriteParseComplete()
            .WriteBindComplete()
            .WriteRowDescription(new FieldDescription(Int4Oid), new FieldDescription(ByteaOid));

        var intValue = new byte[] { 0, 0, 0, 1 };
        var byteValue = new byte[] { 1, 2, 3, 4 };

        var writeBuffer = pgMock.WriteBuffer;
        writeBuffer.WriteByte((byte)BackendMessageCode.DataRow);
        writeBuffer.WriteInt32(4 + 2 + intValue.Length + byteValue.Length + 8);
        writeBuffer.WriteInt16(2);
        writeBuffer.WriteInt32(intValue.Length);
        writeBuffer.WriteBytes(intValue);
        await pgMock.FlushAsync();

        using var cmd = new NpgsqlCommand("SELECT some_int, some_byte FROM some_table", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);

        await reader.ReadAsync();

        reader.GetInt32(0);

        Assert.That(reader.Connector.ReadBuffer.ReadBytesLeft, Is.Zero);
        Assert.That(reader.Connector.ReadBuffer.ReadPosition, Is.Not.Zero);

        writeBuffer.WriteInt32(byteValue.Length);
        writeBuffer.WriteBytes(byteValue);
        await pgMock
            .WriteDataRow(intValue, Enumerable.Range(1, 100).Select(x => (byte)x).ToArray())
            .WriteCommandComplete()
            .WriteReadyForQuery()
            .FlushAsync();

        await reader.GetFieldValueAsync<byte[]>(1);

        Assert.DoesNotThrowAsync(reader.ReadAsync);
    }

    [Test] // #4377
    public async Task Dispose_does_not_swallow_exceptions([Values(true, false)] bool async)
    {
        await using var postmasterMock = PgPostmasterMock.Start(ConnectionString);
        await using var dataSource = CreateDataSource(postmasterMock.ConnectionString);
        await using var conn = await dataSource.OpenConnectionAsync();
        var pgMock = await postmasterMock.WaitForServerConnection();

        // Write responses for the query, but break the connection before sending CommandComplete/ReadyForQuery
        await pgMock
            .WriteParseComplete()
            .WriteBindComplete()
            .WriteRowDescription(new FieldDescription(Int4Oid))
            .WriteDataRow(BitConverter.GetBytes(BinaryPrimitives.ReverseEndianness(1)))
            .FlushAsync();

        using var cmd = new NpgsqlCommand("SELECT 1", conn);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        await reader.ReadAsync();

        pgMock.Close();

        if (async)
            Assert.Throws<NpgsqlException>(() => reader.Dispose());
        else
            Assert.ThrowsAsync<NpgsqlException>(async () => await reader.DisposeAsync());
    }

    [Test]
    public async Task Read_string_as_char()
    {
        await using var conn = await OpenConnectionAsync();

        await using var cmd = conn.CreateCommand();
        cmd.CommandText = "SELECT 'abcdefgh', 'ijklmnop'";

        await using var reader = await cmd.ExecuteReaderAsync(Behavior);
        Assert.That(await reader.ReadAsync());
        Assert.That(reader.GetChar(0), Is.EqualTo('a'));
        if (Behavior == CommandBehavior.SequentialAccess)
            Assert.Throws<InvalidOperationException>(() => reader.GetChar(0));
        else
            Assert.That(reader.GetChar(0), Is.EqualTo('a'));
        Assert.That(reader.GetChar(1), Is.EqualTo('i'));
    }

    #region GetBytes / GetStream

    [Test]
    public async Task GetBytes()
    {
        using var conn = await OpenConnectionAsync();
        var table = await CreateTempTable(conn, "bytes BYTEA");

        // TODO: This is too small to actually test any interesting sequential behavior
        byte[] expected = [1, 2, 3, 4, 5];
        var actual = new byte[expected.Length];
        await conn.ExecuteNonQueryAsync($"INSERT INTO {table} (bytes) VALUES ({EncodeByteaHex(expected)})");

        var query = $"SELECT bytes, 'foo', bytes, 'bar', bytes, bytes FROM {table}";
        using var cmd = new NpgsqlCommand(query, conn);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Read();

        Assert.That(reader.GetBytes(0, 0, actual, 0, 2), Is.EqualTo(2));
        Assert.That(actual[0], Is.EqualTo(expected[0]));
        Assert.That(actual[1], Is.EqualTo(expected[1]));
        Assert.That(reader.GetBytes(0, 0, null, 0, 0), Is.EqualTo(expected.Length), "Bad column length");
        if (IsSequential)
            Assert.That(() => reader.GetBytes(0, 0, actual, 4, 1),
                Throws.Exception.TypeOf<InvalidOperationException>(), "Seek back sequential");
        else
        {
            Assert.That(reader.GetBytes(0, 0, actual, 4, 1), Is.EqualTo(1));
            Assert.That(actual[4], Is.EqualTo(expected[0]));
        }
        Assert.That(reader.GetBytes(0, 2, actual, 2, 3), Is.EqualTo(3));
        Assert.That(actual, Is.EqualTo(expected));
        Assert.That(reader.GetBytes(0, 0, null, 0, 0), Is.EqualTo(expected.Length), "Bad column length");

        Assert.That(reader.GetString(1), Is.EqualTo("foo"));
        reader.GetBytes(2, 0, actual, 0, 2);
        // Jump to another column from the middle of the column
        reader.GetBytes(4, 0, actual, 0, 2);
        Assert.That(reader.GetBytes(4, expected.Length - 1, actual, 0, 2), Is.EqualTo(1),
            "Length greater than data length");
        Assert.That(actual[0], Is.EqualTo(expected[^1]), "Length greater than data length");
        Assert.That(() => reader.GetBytes(4, 0, actual, 0, actual.Length + 1),
            Throws.Exception.TypeOf<IndexOutOfRangeException>(), "Length great than output buffer length");
        // Close in the middle of a column
        reader.GetBytes(5, 0, actual, 0, 2);

        //var result = (byte[]) cmd.ExecuteScalar();
        //Assert.AreEqual(2, result.Length);
    }

    [Test]
    public async Task GetStream_second_time([Values(true, false)] bool isAsync)
    {
        var expected = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
        var streamGetter = BuildStreamGetter(isAsync);

        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand($"SELECT {EncodeByteaHex(expected)}::bytea", conn);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);

        await reader.ReadAsync();

        using var stream = await streamGetter(reader, 0);

        if (IsSequential)
        {
            Assert.That(async () => await streamGetter(reader, 0),
                Throws.Exception.TypeOf<InvalidOperationException>());
        }
        else
        {
            // Non-sequential: getting a second stream disposes the first and returns a fresh one.
            using var stream2 = await streamGetter(reader, 0);
            Assert.That(() => stream.Read(new byte[1]), Throws.TypeOf<ObjectDisposedException>());
            var buf = new byte[8];
            Assert.That(stream2.Read(buf), Is.EqualTo(8));
            Assert.That(buf, Is.EqualTo(expected));
        }
    }

    [Test]
    public async Task GetBytes_before_getstream([Values(true, false)] bool isAsync)
    {
        var expected = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
        var streamGetter = BuildStreamGetter(isAsync);

        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand($"SELECT {EncodeByteaHex(expected)}::bytea", conn);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);

        await reader.ReadAsync();

        // GetBytes with null buffer won't consume column in any way
        Assert.That(reader.GetBytes(0, 0, null, 0, 0), Is.EqualTo(expected.Length), "Bad column length");

        using var stream = await streamGetter(reader, 0);
        Assert.That(stream.Length, Is.EqualTo(expected.Length));
    }

    public static IEnumerable GetStreamCases()
    {
        var binary = MemoryMarshal
            .AsBytes<int>(Enumerable.Range(0, 1024).ToArray())
            .ToArray();
        yield return (binary, binary);

        var bigBinary = MemoryMarshal
            .AsBytes<int>(Enumerable.Range(0, 8193).ToArray())
            .ToArray();
        yield return (bigBinary, bigBinary);

        var bigint = 0xDEADBEEFL;
        var bigintBinary = BitConverter.GetBytes(
            BitConverter.IsLittleEndian
                ? BinaryPrimitives.ReverseEndianness(bigint)
                : bigint);
        yield return (bigint, bigintBinary);
    }

    [Test]
    public async Task GetStream<T>(
        [Values] bool isAsync,
        [ValueSource(nameof(GetStreamCases))] (T Generic, byte[] Binary) value)
    {
        var streamGetter = BuildStreamGetter(isAsync);
        var expected = value.Binary;
        var actual = new byte[expected.Length];

        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand("SELECT @p, @p", conn) { Parameters = { new NpgsqlParameter("p", value.Generic) } };
        using var reader = await cmd.ExecuteReaderAsync(Behavior);

        await reader.ReadAsync();

        using var stream = await streamGetter(reader, 0);
        Assert.That(stream.CanSeek, Is.EqualTo(Behavior == CommandBehavior.Default));
        Assert.That(stream.Length, Is.EqualTo(expected.Length));

        var position = 0;
        while (position < actual.Length)
        {
            if (isAsync)
                position += await stream.ReadAsync(actual, position, actual.Length - position);
            else
                position += stream.Read(actual, position, actual.Length - position);
        }

        Assert.That(actual, Is.EqualTo(expected));
    }

    [Test]
    public async Task Open_stream_when_changing_columns([Values(true, false)] bool isAsync)
    {
        var streamGetter = BuildStreamGetter(isAsync);

        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand(@"SELECT @p, @p", conn);
        var data = new byte[] { 1, 2, 3 };
        cmd.Parameters.Add(new NpgsqlParameter("p", data));
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Read();
        var stream = await streamGetter(reader, 0);
        // ReSharper disable once UnusedVariable
        var v = reader.GetValue(1);
        Assert.That(() => stream.ReadByte(), Throws.Exception.TypeOf<ObjectDisposedException>());
    }

    [Test]
    public async Task Open_stream_when_changing_rows([Values(true, false)] bool isAsync)
    {
        var streamGetter = BuildStreamGetter(isAsync);

        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand(@"SELECT @p", conn);
        var data = new byte[] { 1, 2, 3 };
        cmd.Parameters.Add(new NpgsqlParameter("p", data));
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Read();
        var s1 = await streamGetter(reader, 0);
        reader.Read();
        Assert.That(() => s1.ReadByte(), Throws.Exception.TypeOf<ObjectDisposedException>());
    }

    [Test]
    public async Task GetBytes_with_null([Values(true, false)] bool isAsync)
    {
        var streamGetter = BuildStreamGetter(isAsync);

        using var conn = await OpenConnectionAsync();
        var table = await CreateTempTable(conn, "bytes BYTEA");

        var buf = new byte[8];
        await conn.ExecuteNonQueryAsync($"INSERT INTO {table} (bytes) VALUES (NULL)");
        using var cmd = new NpgsqlCommand($"SELECT bytes FROM {table}", conn);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Read();
        Assert.That(reader.IsDBNull(0), Is.True);
        Assert.That(() => reader.GetBytes(0, 0, buf, 0, 1), Throws.Exception.TypeOf<InvalidCastException>(), "GetBytes");
        Assert.That(async () => await streamGetter(reader, 0), Throws.Exception.TypeOf<InvalidCastException>(), "GetStream");
        Assert.That(() => reader.GetBytes(0, 0, null, 0, 0), Throws.Exception.TypeOf<InvalidCastException>(), "GetBytes with null buffer");
    }

    static Func<NpgsqlDataReader, int, Task<Stream>> BuildStreamGetter(bool isAsync)
        => isAsync
            ? (r, index) => r.GetStreamAsync(index)
            : (r, index) => Task.FromResult(r.GetStream(index));

    [Test]
    public async Task GetStream_after_consuming_column_throws([Values] bool async)
    {
        if (!IsSequential)
            return;

        await using var conn = await OpenConnectionAsync();
        await using var cmd = new NpgsqlCommand(@"SELECT '\xDEADBEEF'::bytea", conn);
        await using var reader = await cmd.ExecuteReaderAsync(CommandBehavior.SequentialAccess);
        await reader.ReadAsync();

        _ = reader.GetFieldValue<byte[]>(0);

        if (async)
            Assert.That(() => reader.GetStreamAsync(0), Throws.Exception.TypeOf<InvalidOperationException>());
        else
            Assert.That(() => reader.GetStream(0), Throws.Exception.TypeOf<InvalidOperationException>());
    }

    [Test]
    public async Task GetStream_in_middle_of_column_throws([Values] bool async)
    {
        if (!IsSequential)
            return;

        await using var conn = await OpenConnectionAsync();
        await using var cmd = new NpgsqlCommand(@"SELECT '\xDEADBEEF'::bytea", conn);
        await using var reader = await cmd.ExecuteReaderAsync(CommandBehavior.SequentialAccess);
        await reader.ReadAsync();

        _ = reader.GetBytes(0, 0, new byte[2], 0, 2);

        if (async)
            Assert.That(() => reader.GetStreamAsync(0), Throws.Exception.TypeOf<InvalidOperationException>());
        else
            Assert.That(() => reader.GetStream(0), Throws.Exception.TypeOf<InvalidOperationException>());
    }

    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/5223")]
    public async Task GetStream_seek()
    {
        // Sequential doesn't allow to seek
        if (IsSequential)
            return;

        await using var conn = await OpenConnectionAsync();
        await using var cmd = conn.CreateCommand();
        cmd.CommandText = "SELECT 'abcdefgh'";
        await using var reader = await cmd.ExecuteReaderAsync();
        await reader.ReadAsync();

        var buffer = new byte[4];

        await using var stream = reader.GetStream(0);
        Assert.That(stream.CanSeek);

        var seekPosition = stream.Seek(-1, SeekOrigin.End);
        Assert.That(seekPosition, Is.EqualTo(stream.Length - 1));
        var read = stream.Read(buffer);
        Assert.That(read, Is.EqualTo(1));
        Assert.That(Encoding.ASCII.GetString(buffer, 0, 1), Is.EqualTo("h"));
        read = stream.Read(buffer);
        Assert.That(read, Is.EqualTo(0));

        seekPosition = stream.Seek(2, SeekOrigin.Begin);
        Assert.That(seekPosition, Is.EqualTo(2));
        read = stream.Read(buffer);
        Assert.That(read, Is.EqualTo(buffer.Length));
        Assert.That(Encoding.ASCII.GetString(buffer), Is.EqualTo("cdef"));

        seekPosition = stream.Seek(-3, SeekOrigin.Current);
        Assert.That(seekPosition, Is.EqualTo(3));
        read = stream.Read(buffer);
        Assert.That(read, Is.EqualTo(buffer.Length));
        Assert.That(Encoding.ASCII.GetString(buffer), Is.EqualTo("defg"));

        stream.Position = 1;
        read = stream.Read(buffer);
        Assert.That(read, Is.EqualTo(buffer.Length));
        Assert.That(Encoding.ASCII.GetString(buffer), Is.EqualTo("bcde"));
    }

    #endregion GetBytes / GetStream

    #region GetChars / GetTextReader

    [Test]
    public async Task GetChars()
    {
        using var conn = await OpenConnectionAsync();
        // TODO: This is too small to actually test any interesting sequential behavior
        const string str = "ABCDE";
        var expected = str.ToCharArray();
        var actual = new char[expected.Length];

        var queryText = $@"SELECT '{str}', 3, '{str}', 4, '{str}', '{str}', '{str}'";
        using var cmd = new NpgsqlCommand(queryText, conn);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Read();

        Assert.That(reader.GetChars(0, 0, actual, 0, 2), Is.EqualTo(2));
        Assert.That(actual[0], Is.EqualTo(expected[0]));
        Assert.That(actual[1], Is.EqualTo(expected[1]));
        if (!IsSequential)
            Assert.That(reader.GetChars(0, 0, null, 0, 0), Is.EqualTo(expected.Length), "Bad column length");
        // Note: Unlike with bytea, finding out the length of the column consumes it (variable-width
        // UTF8 encoding)
        Assert.That(reader.GetChars(2, 0, actual, 0, 2), Is.EqualTo(2));
        if (IsSequential)
            Assert.That(() => reader.GetChars(2, 0, actual, 4, 1), Throws.Exception.TypeOf<InvalidOperationException>(), "Seek back sequential");
        else
        {
            Assert.That(reader.GetChars(2, 0, actual, 4, 1), Is.EqualTo(1));
            Assert.That(actual[4], Is.EqualTo(expected[0]));
        }
        Assert.That(reader.GetChars(2, 2, actual, 2, 3), Is.EqualTo(3));
        Assert.That(actual, Is.EqualTo(expected));
        //Assert.That(reader.GetChars(2, 0, null, 0, 0), Is.EqualTo(expected.Length), "Bad column length");

        Assert.That(() => reader.GetChars(3, 0, null, 0, 0), Throws.Exception.TypeOf<InvalidCastException>(), "GetChars on non-text");
        Assert.That(() => reader.GetChars(3, 0, actual, 0, 1), Throws.Exception.TypeOf<InvalidCastException>(), "GetChars on non-text");
        Assert.That(reader.GetInt32(3), Is.EqualTo(4));
        reader.GetChars(4, 0, actual, 0, 2);
        // Jump to another column from the middle of the column
        reader.GetChars(5, 0, actual, 0, 2);
        Assert.That(reader.GetChars(5, expected.Length - 1, actual, 0, 2), Is.EqualTo(1), "Length greater than data length");
        Assert.That(actual[0], Is.EqualTo(expected[^1]), "Length greater than data length");
        Assert.That(() => reader.GetChars(5, 0, actual, 0, actual.Length + 1), Throws.Exception.TypeOf<IndexOutOfRangeException>(), "Length great than output buffer length");
        // Close in the middle of a column
        reader.GetChars(6, 0, actual, 0, 2);
    }

    [Test]
    public async Task GetChars_AdvanceConsumed()
    {
        const string value = "01234567";

        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand($"SELECT '{value}'", conn);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Read();

        var buffer = new char[2];
        // Don't start at the beginning of the column.
        reader.GetChars(0, 2, buffer, 0, 2);
        reader.GetChars(0, 4, buffer, 0, 2);
        reader.GetChars(0, 6, buffer, 0, 2);

        // Ask for data past the start and the previous point, exercising restart logic.
        if (!IsSequential)
        {
            reader.GetChars(0, 4, buffer, 0, 2);
            reader.GetChars(0, 6, buffer, 0, 2);
        }
    }

    [Test]
    public async Task GetTextReader([Values(true, false)] bool isAsync)
    {
        Func<NpgsqlDataReader, int, Task<TextReader>> textReaderGetter;
        if (isAsync)
            textReaderGetter = (r, index) => r.GetTextReaderAsync(index);
        else
            textReaderGetter = (r, index) => Task.FromResult(r.GetTextReader(index));

        using var conn = await OpenConnectionAsync();
        // TODO: This is too small to actually test any interesting sequential behavior
        const string str = "ABCDE";
        var expected = str.ToCharArray();
        var actual = new char[expected.Length];
        //ExecuteNonQuery(String.Format(@"INSERT INTO data (field_text) VALUES ('{0}')", str));

        var queryText = $@"SELECT '{str}', 'foo'";
        using var cmd = new NpgsqlCommand(queryText, conn);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Read();

        var textReader = await textReaderGetter(reader, 0);
        textReader.Read(actual, 0, 2);
        Assert.That(actual[0], Is.EqualTo(expected[0]));
        Assert.That(actual[1], Is.EqualTo(expected[1]));
        if (IsSequential)
        {
            Assert.That(async () => await textReaderGetter(reader, 0),
                Throws.Exception.TypeOf<InvalidOperationException>(),
                "Sequential text reader twice on same column");
        }
        else
        {
            Assert.That(reader.GetChars(0, 0, actual, 4, 1), Is.EqualTo(1));
        }
        textReader.Read(actual, 2, 1);
        Assert.That(actual[2], Is.EqualTo(expected[2]));
        textReader.Dispose();

        if (IsSequential)
            Assert.That(() => reader.GetChars(0, 0, actual, 4, 1),
                Throws.Exception.TypeOf<InvalidOperationException>(), "Seek back sequential");
        else
        {
            Assert.That(reader.GetChars(0, 0, actual, 4, 1), Is.EqualTo(1));
            Assert.That(actual[4], Is.EqualTo(expected[0]));
        }
        Assert.That(reader.GetString(1), Is.EqualTo("foo"));
    }

    [Test]
    public async Task TextReader_zero_length_column()
    {
        await using var conn = await OpenConnectionAsync();
        await using var cmd = conn.CreateCommand();
        cmd.CommandText = "SELECT ''";

        await using var reader = await cmd.ExecuteReaderAsync(Behavior);
        Assert.That(await reader.ReadAsync());

        using var textReader = reader.GetTextReader(0);
        Assert.That(textReader.Peek(), Is.EqualTo(-1));
        Assert.That(textReader.ReadToEnd(), Is.EqualTo(string.Empty));
    }

    [Test]
    public async Task Open_TextReader_when_changing_columns()
    {
        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand(@"SELECT 'some_text', 'some_text'", conn);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Read();
        var textReader = reader.GetTextReader(0);
        // ReSharper disable once UnusedVariable
        var v = reader.GetValue(1);
        Assert.That(() => textReader.Peek(), Throws.Exception.TypeOf<ObjectDisposedException>());
    }

    [Test]
    public async Task Open_TextReader_when_changing_rows()
    {
        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand(@"SELECT 'some_text', 'some_text'", conn);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Read();
        var tr1 = reader.GetTextReader(0);
        reader.Read();
        Assert.That(() => tr1.Peek(), Throws.Exception.TypeOf<ObjectDisposedException>());
    }

    [Test]
    public async Task GetChars_when_null()
    {
        var buf = new char[8];
        using var conn = await OpenConnectionAsync();
        using var cmd = new NpgsqlCommand("SELECT NULL::TEXT", conn);
        using var reader = await cmd.ExecuteReaderAsync(Behavior);
        reader.Read();
        Assert.That(reader.IsDBNull(0), Is.True);
        Assert.That(() => reader.GetChars(0, 0, buf, 0, 1), Throws.Exception.TypeOf<InvalidCastException>(), "GetChars");
        Assert.That(() => reader.GetTextReader(0), Throws.Exception.TypeOf<InvalidCastException>(), "GetTextReader");
        Assert.That(() => reader.GetChars(0, 0, null, 0, 0), Throws.Exception.TypeOf<InvalidCastException>(), "GetChars with null buffer");
    }

    [Test]
    public async Task Reader_is_reused()
    {
        using var conn = await OpenConnectionAsync();
        NpgsqlDataReader reader1;

        using (var cmd = new NpgsqlCommand("SELECT 8", conn))
        using (reader1 = await cmd.ExecuteReaderAsync(Behavior))
        {
            reader1.Read();
            Assert.That(reader1.GetInt32(0), Is.EqualTo(8));
        }

        using (var cmd = new NpgsqlCommand("SELECT 9", conn))
        using (var reader2 = await cmd.ExecuteReaderAsync(Behavior))
        {
            Assert.That(reader2, Is.SameAs(reader1));
            reader2.Read();
            Assert.That(reader2.GetInt32(0), Is.EqualTo(9));
        }
    }

    [Test]
    public async Task GetTextReader_after_consuming_column_throws([Values] bool async)
    {
        if (!IsSequential)
            return;

        await using var conn = await OpenConnectionAsync();
        await using var cmd = new NpgsqlCommand("SELECT 'foo'", conn);
        await using var reader = await cmd.ExecuteReaderAsync(CommandBehavior.SequentialAccess);
        await reader.ReadAsync();

        _ = reader.GetString(0);

        if (async)
            Assert.That(() => reader.GetTextReaderAsync(0), Throws.Exception.TypeOf<InvalidOperationException>());
        else
            Assert.That(() => reader.GetTextReader(0), Throws.Exception.TypeOf<InvalidOperationException>());
    }

    [Test]
    public async Task GetTextReader_in_middle_of_column_throws([Values] bool async)
    {
        if (!IsSequential)
            return;

        await using var conn = await OpenConnectionAsync();
        await using var cmd = new NpgsqlCommand("SELECT 'foo'", conn);
        await using var reader = await cmd.ExecuteReaderAsync(CommandBehavior.SequentialAccess);
        await reader.ReadAsync();

        _ = reader.GetChars(0, 0, new char[2], 0, 2);

        if (async)
            Assert.That(() => reader.GetTextReaderAsync(0), Throws.Exception.TypeOf<InvalidOperationException>());
        else
            Assert.That(() => reader.GetTextReader(0), Throws.Exception.TypeOf<InvalidOperationException>());
    }

    [Test]
    public async Task GetStream_is_isolated_from_GetChars()
    {
        if (IsSequential)
            return;

        const string str = "ABCDEFGHIJ";
        await using var conn = await OpenConnectionAsync();
        await using var cmd = new NpgsqlCommand($"SELECT '{str}'", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);
        await reader.ReadAsync();

        // GetChars on the column, then get a stream — stream should start from the beginning.
        var charBuf = new char[5];
        Assert.That(reader.GetChars(0, 0, charBuf, 0, 5), Is.EqualTo(5));
        Assert.That(new string(charBuf), Is.EqualTo("ABCDE"));

        await using var stream = reader.GetStream(0);
        Assert.That(stream.CanSeek, Is.True);
        Assert.That(stream.Length, Is.EqualTo(Encoding.UTF8.GetByteCount(str)));
        Assert.That(stream.Position, Is.EqualTo(0));
    }

    [Test]
    public async Task GetStream_survives_reread_of_same_column()
    {
        if (IsSequential)
            return;

        var expected = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
        await using var conn = await OpenConnectionAsync();
        await using var cmd = new NpgsqlCommand($"SELECT {EncodeByteaHex(expected)}::bytea", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);
        await reader.ReadAsync();

        // Get stream, read partially.
        var stream1 = reader.GetStream(0);
        var buf = new byte[3];
        Assert.That(stream1.Read(buf), Is.EqualTo(3));
        Assert.That(buf, Is.EqualTo(new byte[] { 1, 2, 3 }));

        // Getting a second stream on same column disposes the first.
        var stream2 = reader.GetStream(0);
        Assert.That(() => stream1.Read(new byte[1]), Throws.TypeOf<ObjectDisposedException>());

        // Second stream should provide the full data.
        var buf2 = new byte[8];
        Assert.That(stream2.Read(buf2), Is.EqualTo(8));
        Assert.That(buf2, Is.EqualTo(expected));
    }

    [Test]
    public async Task GetTextReader_and_GetChars_interleaved()
    {
        if (IsSequential)
            return;

        const string str = "ABCDEFGHIJKLMNOP";
        await using var conn = await OpenConnectionAsync();
        await using var cmd = new NpgsqlCommand($"SELECT '{str}'", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);
        await reader.ReadAsync();

        // Get a TextReader, read some chars.
        var textReader = reader.GetTextReader(0);
        var buf = new char[4];
        Assert.That(textReader.Read(buf, 0, 4), Is.EqualTo(4));
        Assert.That(new string(buf), Is.EqualTo("ABCD"));

        // Now use GetChars to read from the start — should not affect the TextReader.
        var charsBuf = new char[6];
        Assert.That(reader.GetChars(0, 0, charsBuf, 0, 6), Is.EqualTo(6));
        Assert.That(new string(charsBuf), Is.EqualTo("ABCDEF"));

        // TextReader should still be at its original position.
        Assert.That(textReader.Read(buf, 0, 4), Is.EqualTo(4));
        Assert.That(new string(buf), Is.EqualTo("EFGH"));
    }

    [Test]
    public async Task GetStream_and_GetChars_on_same_column()
    {
        if (IsSequential)
            return;

        const string str = "ABCDEFGHIJ";
        await using var conn = await OpenConnectionAsync();
        await using var cmd = new NpgsqlCommand($"SELECT '{str}'", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);
        await reader.ReadAsync();

        // Get a stream and read partially.
        await using var stream = reader.GetStream(0);
        var buf = new byte[4];
        Assert.That(stream.Read(buf), Is.EqualTo(4));

        // GetChars on the same column — stream should remain valid.
        var charBuf = new char[5];
        Assert.That(reader.GetChars(0, 0, charBuf, 0, 5), Is.EqualTo(5));
        Assert.That(new string(charBuf), Is.EqualTo("ABCDE"));

        // Stream should still be readable from where we left off.
        Assert.That(stream.Read(buf), Is.EqualTo(4));

        // GetChars at a different offset should also work.
        Assert.That(reader.GetChars(0, 5, charBuf, 0, 5), Is.EqualTo(5));
        Assert.That(new string(charBuf), Is.EqualTo("FGHIJ"));
    }

    [Test]
    public async Task GetStream_seek_with_SubReadStream()
    {
        if (IsSequential)
            return;

        await using var conn = await OpenConnectionAsync();
        await using var cmd = new NpgsqlCommand("SELECT 'abcdefgh'::bytea", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);
        await reader.ReadAsync();

        await using var stream = reader.GetStream(0);
        Assert.That(stream.CanSeek, Is.True);

        // Read, seek back, read again — isolated from ReadPosition.
        var buf = new byte[4];
        Assert.That(stream.Read(buf), Is.EqualTo(4));

        stream.Position = 0;
        var buf2 = new byte[4];
        Assert.That(stream.Read(buf2), Is.EqualTo(4));
        Assert.That(buf2, Is.EqualTo(buf));

        // Seek to end, confirm empty.
        stream.Seek(0, SeekOrigin.End);
        Assert.That(stream.Read(buf), Is.EqualTo(0));
    }

    [Test]
    public async Task GetChars_after_unconsumed_GetStream()
    {
        if (IsSequential)
            return;

        const string str = "ABCDEFGHIJ";
        await using var conn = await OpenConnectionAsync();
        await using var cmd = new NpgsqlCommand($"SELECT '{str}'", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);
        await reader.ReadAsync();

        // Get a stream but don't read from it.
        var stream = reader.GetStream(0);

        // GetChars should work — SubReadStream is isolated.
        var charBuf = new char[5];
        Assert.That(reader.GetChars(0, 0, charBuf, 0, 5), Is.EqualTo(5));
        Assert.That(new string(charBuf), Is.EqualTo("ABCDE"));

        // Stream is still valid.
        var buf = new byte[3];
        Assert.That(stream.Read(buf), Is.EqualTo(3));
    }

    [Test]
    public async Task Multiple_GetChars_calls_after_GetTextReader()
    {
        if (IsSequential)
            return;

        const string str = "ABCDEFGHIJ";
        await using var conn = await OpenConnectionAsync();
        await using var cmd = new NpgsqlCommand($"SELECT '{str}'", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);
        await reader.ReadAsync();

        var textReader = reader.GetTextReader(0);
        var buf = new char[2];
        textReader.Read(buf, 0, 2);
        Assert.That(new string(buf), Is.EqualTo("AB"));

        // Multiple GetChars calls at different offsets should all work.
        var charBuf = new char[3];
        Assert.That(reader.GetChars(0, 0, charBuf, 0, 3), Is.EqualTo(3));
        Assert.That(new string(charBuf), Is.EqualTo("ABC"));

        Assert.That(reader.GetChars(0, 5, charBuf, 0, 3), Is.EqualTo(3));
        Assert.That(new string(charBuf), Is.EqualTo("FGH"));

        // TextReader should still work from where it was.
        textReader.Read(buf, 0, 2);
        Assert.That(new string(buf), Is.EqualTo("CD"));
    }

    [Test]
    public async Task Sequential_GetChars_advances_field_position([Values] bool fitsInBuffer)
    {
        // Invariant: GetChars must always advance ReadPosition (even when data is fully buffered),
        // so that FieldAtStart correctly reflects consumption. This ensures the sequential seek
        // guard blocks non-resumable re-reads after GetChars has consumed data.
        // This is important for behavioral consistency across columns. As an optimization
        // that skips ReadPosition advancement (reading from a view over the buffer) would pass the sequential seek guard.
        if (!IsSequential)
            return;

        await using var conn = await OpenConnectionAsync();
        var bufferSize = conn.Settings.ReadBufferSize;
        var str = new string('x', fitsInBuffer ? 10 : bufferSize * 2);

        await using var cmd = new NpgsqlCommand($"SELECT '{str}'", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);
        await reader.ReadAsync();

        // GetChars consumes part of the column.
        var charBuf = new char[5];
        Assert.That(reader.GetChars(0, 0, charBuf, 0, 5), Is.EqualTo(5));

        // A non-resumable read on the same column should throw — field is no longer at start.
        Assert.That(() => reader.GetString(0), Throws.Exception.TypeOf<InvalidOperationException>());
    }

    #endregion GetChars / GetTextReader

    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/5450")]
    public async Task EndRead_StreamActive([Values]bool async)
    {
        const int columnLength = 1;

        await using var conn = await OpenConnectionAsync();
        var buffer = conn.Connector!.ReadBuffer;
        buffer.AddBytesToRead(columnLength);
        var reader = buffer.PgReader;
        reader.Init(DataFormat.Binary, columnLength, resumable: false);
        if (async)
            await reader.StartReadAsync(new(DataFormat.Binary, Size.Unknown), CancellationToken.None);
        else
            reader.StartRead(new(DataFormat.Binary, Size.Unknown));

        await using (var _ = reader.GetStream())
        {
            if (async)
                Assert.DoesNotThrowAsync(async () => await reader.EndReadAsync());
            else
                Assert.DoesNotThrow(() => reader.EndRead());
        }

        reader.Commit();
    }

    [Test, Description("Tests that everything goes well when a type handler generates a NpgsqlSafeReadException")]
    public async Task SafeReadException()
    {
        var dataSourceBuilder = CreateDataSourceBuilder();
        // Temporarily reroute integer to go to a type handler which generates SafeReadExceptions
        dataSourceBuilder.AddTypeInfoResolverFactory(new ExplodingTypeHandlerResolverFactory(safe: true));
        await using var dataSource = dataSourceBuilder.Build();
        await using var connection = await dataSource.OpenConnectionAsync();

        await using var cmd = new NpgsqlCommand(@"SELECT 1, 'hello'", connection);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);
        await reader.ReadAsync();
        Assert.That(() => reader.GetInt32(0),
            Throws.Exception.With.Message.EqualTo("Safe read exception as requested"));
        Assert.That(reader.GetString(1), Is.EqualTo("hello"));
    }

    [Test, Description("Tests that when a type handler generates an exception that isn't a NpgsqlSafeReadException, the connection is properly broken")]
    public async Task Non_SafeReadException()
    {
        var dataSourceBuilder = CreateDataSourceBuilder();
        // Temporarily reroute integer to go to a type handler which generates some exception
        dataSourceBuilder.AddTypeInfoResolverFactory(new ExplodingTypeHandlerResolverFactory(safe: false));
        await using var dataSource = dataSourceBuilder.Build();
        await using var connection = await dataSource.OpenConnectionAsync();

        await using var cmd = new NpgsqlCommand(@"SELECT 1, 'hello'", connection);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);
        await reader.ReadAsync();
        Assert.That(() => reader.GetInt32(0), Throws.Exception.With.Message.EqualTo("Broken"));
        Assert.That(connection.FullState, Is.EqualTo(ConnectionState.Broken));
        Assert.That(connection.State, Is.EqualTo(ConnectionState.Closed));
    }

    [Test, Description("Per-ordinal conversion cache must be invariant in advertised type vs requested read type — a chain-compatible cached entry from a prior typed read must not satisfy a query for a different type, the resolver chain has to be re-consulted.")]
    public async Task ReaderCache_invariant_in_read_type()
    {
        var dataSourceBuilder = CreateDataSourceBuilder();
        dataSourceBuilder.AddTypeInfoResolverFactory(new CustomStreamResolverFactory());
        await using var dataSource = dataSourceBuilder.Build();
        await using var connection = await dataSource.OpenConnectionAsync();

        await using var cmd = new NpgsqlCommand(@"SELECT '\x01'::bytea UNION ALL SELECT '\x02'::bytea", connection);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);

        Assert.That(await reader.ReadAsync(), Is.True);
        using var custom = reader.GetFieldValue<CustomStream>(0);
        Assert.That(custom, Is.InstanceOf<CustomStream>());

        Assert.That(await reader.ReadAsync(), Is.True);
        using var general = reader.GetFieldValue<Stream>(0);
        Assert.That(general, Is.Not.InstanceOf<CustomStream>(),
            "Reader cache aliased the CustomStream-specific info onto a Stream query — the resolver chain must be re-consulted on type change.");
    }

    #region Cancellation

    [Test, Description("Cancels ReadAsync via the NpgsqlCommand.Cancel, with successful PG cancellation")]
    public async Task ReadAsync_cancel_command_soft()
    {
        await using var postmasterMock = PgPostmasterMock.Start(ConnectionString);
        await using var dataSource = CreateDataSource(postmasterMock.ConnectionString);
        await using var conn = await dataSource.OpenConnectionAsync();

        // Write responses to the query we're about to send, with a single data row (we'll attempt to read two)
        var pgMock = await postmasterMock.WaitForServerConnection();
        await pgMock
            .WriteParseComplete()
            .WriteBindComplete()
            .WriteRowDescription(new FieldDescription(Int4Oid))
            .WriteDataRow(BitConverter.GetBytes(BinaryPrimitives.ReverseEndianness(1)))
            .FlushAsync();

        using var cmd = new NpgsqlCommand("SELECT some_int FROM some_table", conn);
        await using (var reader = await cmd.ExecuteReaderAsync(Behavior))
        {
            // Successfully read the first row
            Assert.That(await reader.ReadAsync());
            Assert.That(reader.GetInt32(0), Is.EqualTo(1));

            // Attempt to read the second row - simulate blocking and cancellation
            var task = reader.ReadAsync();
            cmd.Cancel();

            var processId = (await postmasterMock.WaitForCancellationRequest()).ProcessId;
            Assert.That(processId, Is.EqualTo(conn.ProcessID));

            await pgMock
                .WriteErrorResponse(PostgresErrorCodes.QueryCanceled)
                .WriteReadyForQuery()
                .FlushAsync();

            var exception = Assert.ThrowsAsync<OperationCanceledException>(async () => await task)!;
            Assert.That(exception.InnerException,
                Is.TypeOf<PostgresException>().With.Property(nameof(PostgresException.SqlState)).EqualTo(PostgresErrorCodes.QueryCanceled));

            Assert.That(conn.FullState, Is.EqualTo(ConnectionState.Open | ConnectionState.Fetching));
        }

        await pgMock.WriteScalarResponseAndFlush(1);
        Assert.That(await conn.ExecuteScalarAsync("SELECT 1"), Is.EqualTo(1));
    }

    [Test, Description("Cancels ReadAsync via the cancellation token, with successful PG cancellation")]
    public async Task ReadAsync_cancel_soft()
    {
        await using var postmasterMock = PgPostmasterMock.Start(ConnectionString);
        await using var dataSource = CreateDataSource(postmasterMock.ConnectionString);
        await using var conn = await dataSource.OpenConnectionAsync();

        // Write responses to the query we're about to send, with a single data row (we'll attempt to read two)
        var pgMock = await postmasterMock.WaitForServerConnection();
        await pgMock
            .WriteParseComplete()
            .WriteBindComplete()
            .WriteRowDescription(new FieldDescription(Int4Oid))
            .WriteDataRow(BitConverter.GetBytes(BinaryPrimitives.ReverseEndianness(1)))
            .FlushAsync();

        using var cmd = new NpgsqlCommand("SELECT some_int FROM some_table", conn);
        await using (var reader = await cmd.ExecuteReaderAsync(Behavior))
        {
            // Successfully read the first row
            Assert.That(await reader.ReadAsync());
            Assert.That(reader.GetInt32(0), Is.EqualTo(1));

            // Attempt to read the second row - simulate blocking and cancellation
            var cancellationSource = new CancellationTokenSource();
            var task = reader.ReadAsync(cancellationSource.Token);
            cancellationSource.Cancel();

            var processId = (await postmasterMock.WaitForCancellationRequest()).ProcessId;
            Assert.That(processId, Is.EqualTo(conn.ProcessID));

            await pgMock
                .WriteErrorResponse(PostgresErrorCodes.QueryCanceled)
                .WriteReadyForQuery()
                .FlushAsync();

            var exception = Assert.ThrowsAsync<OperationCanceledException>(async () => await task)!;
            Assert.That(exception.InnerException,
                Is.TypeOf<PostgresException>().With.Property(nameof(PostgresException.SqlState)).EqualTo(PostgresErrorCodes.QueryCanceled));
            Assert.That(exception.CancellationToken, Is.EqualTo(cancellationSource.Token));

            Assert.That(conn.FullState, Is.EqualTo(ConnectionState.Open | ConnectionState.Fetching));
        }

        await pgMock.WriteScalarResponseAndFlush(1);
        Assert.That(await conn.ExecuteScalarAsync("SELECT 1"), Is.EqualTo(1));
    }

    [Test, Description("Cancels NextResultAsync via the cancellation token, with successful PG cancellation")]
    public async Task NextResult_cancel_soft()
    {
        await using var postmasterMock = PgPostmasterMock.Start(ConnectionString);
        await using var dataSource = CreateDataSource(postmasterMock.ConnectionString);
        await using var conn = await dataSource.OpenConnectionAsync();

        // Write responses to the query we're about to send, only for the first resultset (we'll attempt to read two)
        var pgMock = await postmasterMock.WaitForServerConnection();
        await pgMock
            .WriteParseComplete()
            .WriteBindComplete()
            .WriteRowDescription(new FieldDescription(Int4Oid))
            .WriteDataRow(BitConverter.GetBytes(BinaryPrimitives.ReverseEndianness(1)))
            .WriteCommandComplete()
            .FlushAsync();

        using var cmd = new NpgsqlCommand("SELECT 1; SELECT 2", conn);
        await using (var reader = await cmd.ExecuteReaderAsync(Behavior))
        {
            // Successfully read the first resultset
            Assert.That(await reader.ReadAsync());
            Assert.That(reader.GetInt32(0), Is.EqualTo(1));

            // Attempt to advance to the second resultset - simulate blocking and cancellation
            var cancellationSource = new CancellationTokenSource();
            var task = reader.NextResultAsync(cancellationSource.Token);
            cancellationSource.Cancel();

            var processId = (await postmasterMock.WaitForCancellationRequest()).ProcessId;
            Assert.That(processId, Is.EqualTo(conn.ProcessID));

            await pgMock
                .WriteErrorResponse(PostgresErrorCodes.QueryCanceled)
                .WriteReadyForQuery()
                .FlushAsync();

            var exception = Assert.ThrowsAsync<OperationCanceledException>(async () => await task)!;
            Assert.That(exception.InnerException,
                Is.TypeOf<PostgresException>().With.Property(nameof(PostgresException.SqlState)).EqualTo(PostgresErrorCodes.QueryCanceled));
            Assert.That(exception.CancellationToken, Is.EqualTo(cancellationSource.Token));

            Assert.That(conn.FullState, Is.EqualTo(ConnectionState.Open | ConnectionState.Fetching));
        }

        await pgMock.WriteScalarResponseAndFlush(1);
        Assert.That(await conn.ExecuteScalarAsync("SELECT 1"), Is.EqualTo(1));
    }

    [Test, Description("Cancels ReadAsync via the cancellation token, with unsuccessful PG cancellation (socket break)")]
    public async Task ReadAsync_cancel_hard([Values(true, false)] bool passCancelledToken)
    {
        await using var postmasterMock = PgPostmasterMock.Start(ConnectionString);
        await using var dataSource = CreateDataSource(postmasterMock.ConnectionString);
        await using var conn = await dataSource.OpenConnectionAsync();

        // Write responses to the query we're about to send, with a single data row (we'll attempt to read two)
        var pgMock = await postmasterMock.WaitForServerConnection();
        await pgMock
            .WriteParseComplete()
            .WriteBindComplete()
            .WriteRowDescription(new FieldDescription(Int4Oid))
            .WriteDataRow(BitConverter.GetBytes(BinaryPrimitives.ReverseEndianness(1)))
            .FlushAsync();

        using var cmd = new NpgsqlCommand("SELECT some_int FROM some_table", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);

        // Successfully read the first row
        Assert.That(await reader.ReadAsync());
        Assert.That(reader.GetInt32(0), Is.EqualTo(1));

        // Attempt to read the second row - simulate blocking and cancellation
        var cancellationSource = new CancellationTokenSource();
        if (passCancelledToken)
            cancellationSource.Cancel();
        var task = reader.ReadAsync(cancellationSource.Token);
        cancellationSource.Cancel();

        var processId = (await postmasterMock.WaitForCancellationRequest()).ProcessId;
        Assert.That(processId, Is.EqualTo(conn.ProcessID));

        // Send no response from server, wait for the cancellation attempt to time out
        var exception = Assert.ThrowsAsync<OperationCanceledException>(async () => await task)!;
        Assert.That(exception.InnerException, Is.TypeOf<TimeoutException>());
        Assert.That(exception.CancellationToken, Is.EqualTo(cancellationSource.Token));

        Assert.That(conn.FullState, Is.EqualTo(ConnectionState.Broken));
    }

    [Test, Description("Cancels NextResultAsync via the cancellation token, with unsuccessful PG cancellation (socket break)")]
    public async Task NextResultAsync_cancel_hard([Values(true, false)] bool passCancelledToken)
    {
        await using var postmasterMock = PgPostmasterMock.Start(ConnectionString);
        await using var dataSource = CreateDataSource(postmasterMock.ConnectionString);
        await using var conn = await dataSource.OpenConnectionAsync();

        // Write responses to the query we're about to send, with a single data row (we'll attempt to read two)
        var pgMock = await postmasterMock.WaitForServerConnection();
        await pgMock
            .WriteParseComplete()
            .WriteBindComplete()
            .WriteRowDescription(new FieldDescription(Int4Oid))
            .WriteDataRow(BitConverter.GetBytes(BinaryPrimitives.ReverseEndianness(1)))
            .WriteCommandComplete()
            .FlushAsync();

        using var cmd = new NpgsqlCommand("SELECT some_int FROM some_table", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);

        // Successfully read the first resultset
        Assert.That(await reader.ReadAsync());
        Assert.That(reader.GetInt32(0), Is.EqualTo(1));

        // Attempt to read the second row - simulate blocking and cancellation
        var cancellationSource = new CancellationTokenSource();
        if (passCancelledToken)
            cancellationSource.Cancel();
        var task = reader.NextResultAsync(cancellationSource.Token);
        cancellationSource.Cancel();

        var processId = (await postmasterMock.WaitForCancellationRequest()).ProcessId;
        Assert.That(processId, Is.EqualTo(conn.ProcessID));

        // Send no response from server, wait for the cancellation attempt to time out
        var exception = Assert.ThrowsAsync<OperationCanceledException>(async () => await task)!;
        Assert.That(exception.InnerException, Is.TypeOf<TimeoutException>());
        Assert.That(exception.CancellationToken, Is.EqualTo(cancellationSource.Token));

        Assert.That(conn.FullState, Is.EqualTo(ConnectionState.Broken));
    }

    [Test, Description("Cancels sequential ReadAsGetFieldValueAsync")]
    public async Task GetFieldValueAsync_sequential_cancel([Values(true, false)] bool passCancelledToken)
    {
        if (!IsSequential)
            return;

        await using var postmasterMock = PgPostmasterMock.Start(ConnectionString);
        await using var dataSource = CreateDataSource(postmasterMock.ConnectionString);
        await using var conn = await dataSource.OpenConnectionAsync();

        // Write responses to the query we're about to send, with a single data row (we'll attempt to read two)
        var pgMock = await postmasterMock.WaitForServerConnection();
        await pgMock
            .WriteParseComplete()
            .WriteBindComplete()
            .WriteRowDescription(new FieldDescription(ByteaOid))
            .WriteDataRowWithFlush(new byte[10000]);

        using var cmd = new NpgsqlCommand("SELECT some_bytea FROM some_table", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);

        await reader.ReadAsync();

        using var cts = new CancellationTokenSource();
        if (passCancelledToken)
            cts.Cancel();
        var task = reader.GetFieldValueAsync<byte[]>(0, cts.Token);
        cts.Cancel();

        var exception = Assert.ThrowsAsync<OperationCanceledException>(async () => await task)!;
        Assert.That(exception.InnerException, Is.Null);

        Assert.That(conn.FullState, Is.EqualTo(ConnectionState.Broken));
    }

    [Test, Description("Cancels sequential ReadAsGetFieldValueAsync")]
    public async Task IsDBNullAsync_sequential_cancel([Values(true, false)] bool passCancelledToken)
    {
        if (!IsSequential)
            return;

        await using var postmasterMock = PgPostmasterMock.Start(ConnectionString);
        await using var dataSource = CreateDataSource(postmasterMock.ConnectionString);
        await using var conn = await dataSource.OpenConnectionAsync();

        // Write responses to the query we're about to send, with a single data row (we'll attempt to read two)
        var pgMock = await postmasterMock.WaitForServerConnection();
        await pgMock
            .WriteParseComplete()
            .WriteBindComplete()
            .WriteRowDescription(new FieldDescription(ByteaOid), new FieldDescription(Int4Oid))
            .WriteDataRowWithFlush(new byte[10000], new byte[4]);

        using var cmd = new NpgsqlCommand("SELECT some_bytea, some_int FROM some_table", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);

        await reader.ReadAsync();

        using var cts = new CancellationTokenSource();
        if (passCancelledToken)
            cts.Cancel();
        var task = reader.IsDBNullAsync(1, cts.Token);
        cts.Cancel();

        var exception = Assert.ThrowsAsync<OperationCanceledException>(async () => await task)!;
        Assert.That(exception.InnerException, Is.Null);

        Assert.That(conn.FullState, Is.EqualTo(ConnectionState.Broken));
    }

    #endregion Cancellation

    #region Timeout

    [Test, Description("Timeouts sequential ReadAsGetFieldValueAsync")]
    public async Task GetFieldValueAsync_sequential_timeout()
    {
        if (!IsSequential)
            return;

        var csb = new NpgsqlConnectionStringBuilder(ConnectionString)
        {
            CommandTimeout = 3,
            CancellationTimeout = 15000
        };

        await using var postmasterMock = PgPostmasterMock.Start(csb.ToString());
        await using var dataSource = CreateDataSource(postmasterMock.ConnectionString);
        await using var conn = await dataSource.OpenConnectionAsync();

        // Write responses to the query we're about to send, with a single data row (we'll attempt to read two)
        var pgMock = await postmasterMock.WaitForServerConnection();
        await pgMock
            .WriteParseComplete()
            .WriteBindComplete()
            .WriteRowDescription(new FieldDescription(ByteaOid))
            .WriteDataRowWithFlush(new byte[10000]);

        using var cmd = new NpgsqlCommand("SELECT some_bytea FROM some_table", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);

        await reader.ReadAsync();

        var task = reader.GetFieldValueAsync<byte[]>(0);

        var exception = Assert.ThrowsAsync<NpgsqlException>(async () => await task)!;
        Assert.That(exception.InnerException, Is.TypeOf<TimeoutException>());

        Assert.That(conn.FullState, Is.EqualTo(ConnectionState.Broken));
    }

    [Test, Description("Timeouts sequential IsDBNullAsync")]
    public async Task IsDBNullAsync_sequential_timeout()
    {
        if (!IsSequential)
            return;

        var csb = new NpgsqlConnectionStringBuilder(ConnectionString)
        {
            CommandTimeout = 3,
            CancellationTimeout = 15000
        };

        await using var postmasterMock = PgPostmasterMock.Start(csb.ToString());
        await using var dataSource = CreateDataSource(postmasterMock.ConnectionString);
        await using var conn = await dataSource.OpenConnectionAsync();

        // Write responses to the query we're about to send, with a single data row (we'll attempt to read two)
        var pgMock = await postmasterMock.WaitForServerConnection();
        await pgMock
            .WriteParseComplete()
            .WriteBindComplete()
            .WriteRowDescription(new FieldDescription(ByteaOid), new FieldDescription(Int4Oid))
            .WriteDataRowWithFlush(new byte[10000], new byte[4]);

        using var cmd = new NpgsqlCommand("SELECT some_bytea, some_int FROM some_table", conn);
        await using var reader = await cmd.ExecuteReaderAsync(Behavior);

        await reader.ReadAsync();

        var task = reader.GetFieldValueAsync<byte[]>(0);

        var exception = Assert.ThrowsAsync<NpgsqlException>(async () => await task)!;
        Assert.That(exception.InnerException, Is.TypeOf<TimeoutException>());

        Assert.That(conn.FullState, Is.EqualTo(ConnectionState.Broken));
    }

    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/3446")]
    public async Task Bug3446()
    {
        await using var postmasterMock = PgPostmasterMock.Start(ConnectionString);
        await using var dataSource = CreateDataSource(postmasterMock.ConnectionString);
        await using var conn = await dataSource.OpenConnectionAsync();

        var pgMock = await postmasterMock.WaitForServerConnection();
        await pgMock
            .WriteParseComplete()
            .WriteBindComplete()
            .WriteRowDescription(new FieldDescription(Int4Oid))
            .WriteDataRow(new byte[4])
            .FlushAsync();

        using var cmd = new NpgsqlCommand("SELECT some_int FROM some_table", conn);
        await using (var reader = await cmd.ExecuteReaderAsync(Behavior))
        {
            await reader.ReadAsync();
            cmd.Cancel();
            await postmasterMock.WaitForCancellationRequest();
            await pgMock
                .WriteErrorResponse(PostgresErrorCodes.QueryCanceled)
                .WriteReadyForQuery()
                .FlushAsync();
        }

        Assert.That(conn.Connector!.State, Is.EqualTo(ConnectorState.Ready));
    }

    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/6160")]
    [Description("Consuming result set shouldn't go infinite in case connection is broken")]
    public async Task Bug6160()
    {
        var csb = new NpgsqlConnectionStringBuilder(ConnectionString)
        {
            // Set to -1 to trigger immediate connection break on timeout
            CancellationTimeout = -1,
            CommandTimeout = 1
        };
        await using var postmasterMock = PgPostmasterMock.Start(csb.ConnectionString);
        await using var dataSource = CreateDataSource(postmasterMock.ConnectionString);
        await using var conn = await dataSource.OpenConnectionAsync();

        var pgMock = await postmasterMock.WaitForServerConnection();
        await pgMock
            .WriteParseComplete()
            .WriteBindComplete()
            .WriteRowDescription(new FieldDescription(Int4Oid))
            .WriteDataRow(new byte[4])
            .FlushAsync();

        await using var cmd = new NpgsqlCommand("SELECT 1", conn);
        await using (var reader = await cmd.ExecuteReaderAsync(Behavior | CommandBehavior.SingleRow))
        {
            await reader.ReadAsync();
            // The second read will try to consume the whole resultset due to CommandBehavior.SingleRow
            // Which will fail with timeout (and immediate connection break) since we didn't send anything else beside the first row
            var ex = Assert.ThrowsAsync<NpgsqlException>(async () => await reader.ReadAsync())!;
            Assert.That(ex.InnerException, Is.TypeOf<TimeoutException>());

            Assert.That(conn.State, Is.EqualTo(ConnectionState.Closed));
        }
    }

    #endregion

    #region Initialization / setup / teardown

    // ReSharper disable InconsistentNaming
    readonly bool IsSequential;
    readonly CommandBehavior Behavior;
    // ReSharper restore InconsistentNaming

    public ReaderTests(CommandBehavior behavior)
    {
        Behavior = behavior;
        IsSequential = (Behavior & CommandBehavior.SequentialAccess) != 0;
    }

    #endregion
}

#region Mock Type Handlers

sealed class ExplodingTypeHandlerResolverFactory(bool safe) : PgTypeInfoResolverFactory
{
    public override IPgTypeInfoResolver CreateResolver() => new Resolver(safe);
    public override IPgTypeInfoResolver? CreateArrayResolver() => null;

    sealed class Resolver(bool safe) : IPgTypeInfoResolver
    {
        public PgTypeInfo? GetTypeInfo(Type? type, DataTypeName? dataTypeName, PgSerializerOptions options)
        {
            if (dataTypeName == DataTypeNames.Int4 && (type == typeof(int) || type is null))
                return new PgConcreteTypeInfo(options, new ExplodingTypeHandler(safe), DataTypeNames.Int4);

            return null;
        }
    }
}

sealed class CustomStream : MemoryStream;

sealed class CustomStreamResolverFactory : PgTypeInfoResolverFactory
{
    public override IPgTypeInfoResolver CreateResolver() => new Resolver();
    public override IPgTypeInfoResolver? CreateArrayResolver() => null;

    sealed class Resolver : IPgTypeInfoResolver
    {
        // Converter handles Stream but the info advertises CustomStream — HasExactType=false (under-reporting), which is
        // the construction shape that previously enabled the cache's variance-tolerant CanReadTo to alias this info onto
        // a Stream query.
        public PgTypeInfo? GetTypeInfo(Type? type, DataTypeName? dataTypeName, PgSerializerOptions options)
            => type == typeof(CustomStream) && dataTypeName == DataTypeNames.Bytea
                ? new PgConcreteTypeInfo(options, new CustomStreamConverter(), DataTypeNames.Bytea, requestedType: typeof(CustomStream))
                {
                    // Under-reporting: converter produces Stream values that are actually CustomStream instances.
                    SupportsReading = true,
                    SupportsWriting = false,
                }
                : null;
    }
}

sealed class CustomStreamConverter : PgStreamingConverter<Stream>
{
    public override Stream Read(PgReader reader)
    {
        using var bytes = reader.GetStream();
        var ms = new CustomStream();
        bytes.CopyTo(ms);
        ms.Position = 0;
        return ms;
    }

    public override async ValueTask<Stream> ReadAsync(PgReader reader, CancellationToken cancellationToken = default)
    {
        await using var bytes = reader.GetStream();
        var ms = new CustomStream();
        await bytes.CopyToAsync(ms, cancellationToken).ConfigureAwait(false);
        ms.Position = 0;
        return ms;
    }

    protected override Size BindValue(in BindContext context, Stream value, ref object? writeState) => throw new NotSupportedException();
    public override void Write(PgWriter writer, Stream value) => throw new NotSupportedException();
    public override ValueTask WriteAsync(PgWriter writer, Stream value, CancellationToken cancellationToken = default) => throw new NotSupportedException();
}

class ExplodingTypeHandler : PgBufferedConverter<int>
{
    readonly bool _safe;

    internal ExplodingTypeHandler(bool safe) => _safe = safe;

    protected override Size BindValue(in BindContext context, int value, ref object? writeState)
        => throw new NotSupportedException();

    public override bool CanConvert(DataFormat format, out BufferRequirements bufferRequirements)
    {
        bufferRequirements = BufferRequirements.Value;
        return format is DataFormat.Binary;
    }

    public override void Write(PgWriter writer, int value)
        => throw new NotSupportedException();

    public override int Read(PgReader reader)
    {
        if (_safe)
            throw new Exception("Safe read exception as requested");

        reader.BreakConnection();
        return default;
    }
}

#endregion