Java
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1/*
2* Copyright (C) 2008 The Guava Authors
3*
4* Licensed under the Apache License, Version 2.0 (the "License");
5* you may not use this file except in compliance with the License.
6* You may obtain a copy of the License at
7*
8* http://www.apache.org/licenses/LICENSE-2.0
9*
10* Unless required by applicable law or agreed to in writing, software
11* distributed under the License is distributed on an "AS IS" BASIS,
12* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13* See the License for the specific language governing permissions and
14* limitations under the License.
15*/
16
17package com.google.common.collect.testing.testers;
18
19import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_KEYS;
20import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_VALUES;
21
22import com.google.common.annotations.GwtCompatible;
23import com.google.common.collect.testing.AbstractMapTester;
24import com.google.common.collect.testing.features.CollectionSize;
25import com.google.common.collect.testing.features.MapFeature;
26import java.util.Collection;
27import java.util.Map.Entry;
28import org.junit.Ignore;
29
30/**
31* Tests {@link java.util.Map#hashCode}.
32*
33* @author George van den Driessche
34* @author Chris Povirk
35*/
36@GwtCompatible
37@Ignore // Affects only Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
38@SuppressWarnings("JUnit4ClassUsedInJUnit3")
39public class MapHashCodeTester<K, V> extends AbstractMapTester<K, V> {
40public void testHashCode() {
41int expectedHashCode = 0;
42for (Entry<K, V> entry : getSampleEntries()) {
43expectedHashCode += hash(entry);
44}
45assertEquals(
46"A Map's hashCode() should be the sum of those of its entries.",
47expectedHashCode,
48getMap().hashCode());
49}
50
51@CollectionSize.Require(absent = CollectionSize.ZERO)
52@MapFeature.Require(ALLOWS_NULL_KEYS)
53public void testHashCode_containingNullKey() {
54Entry<K, V> entryWithNull = entry(null, v3());
55runEntryWithNullTest(entryWithNull);
56}
57
58@CollectionSize.Require(absent = CollectionSize.ZERO)
59@MapFeature.Require(ALLOWS_NULL_VALUES)
60public void testHashCode_containingNullValue() {
61Entry<K, V> entryWithNull = entry(k3(), null);
62runEntryWithNullTest(entryWithNull);
63}
64
65private void runEntryWithNullTest(Entry<K, V> entryWithNull) {
66Collection<Entry<K, V>> entries = getSampleEntries(getNumEntries() - 1);
67
68entries.add(entryWithNull);
69
70int expectedHashCode = 0;
71for (Entry<K, V> entry : entries) {
72expectedHashCode += hash(entry);
73}
74
75resetContainer(getSubjectGenerator().create(entries.toArray()));
76assertEquals(
77"A Map's hashCode() should be the sum of those of its entries (where "
78+ "a null element in an entry counts as having a hash of zero).",
79expectedHashCode,
80getMap().hashCode());
81}
82
83private static int hash(Entry<?, ?> e) {
84return (e.getKey() == null ? 0 : e.getKey().hashCode())
85^ (e.getValue() == null ? 0 : e.getValue().hashCode());
86}
87}
88