Coverage Summary for Class: MapHashCodeTester (com.google.common.collect.testing.testers)

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 
17 package com.google.common.collect.testing.testers;
18 
19 import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_KEYS;
20 import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_VALUES;
21 
22 import com.google.common.annotations.GwtCompatible;
23 import com.google.common.collect.testing.AbstractMapTester;
24 import com.google.common.collect.testing.features.CollectionSize;
25 import com.google.common.collect.testing.features.MapFeature;
26 import java.util.Collection;
27 import java.util.Map.Entry;
28 import 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 public class MapHashCodeTester<K, V> extends AbstractMapTester<K, V> {
39   public void testHashCode() {
40     int expectedHashCode = 0;
41     for (Entry<K, V> entry : getSampleEntries()) {
42       expectedHashCode += hash(entry);
43     }
44     assertEquals(
45         "A Map's hashCode() should be the sum of those of its entries.",
46         expectedHashCode,
47         getMap().hashCode());
48   }
49 
50   @CollectionSize.Require(absent = CollectionSize.ZERO)
51   @MapFeature.Require(ALLOWS_NULL_KEYS)
52   public void testHashCode_containingNullKey() {
53     Entry<K, V> entryWithNull = entry(null, v3());
54     runEntryWithNullTest(entryWithNull);
55   }
56 
57   @CollectionSize.Require(absent = CollectionSize.ZERO)
58   @MapFeature.Require(ALLOWS_NULL_VALUES)
59   public void testHashCode_containingNullValue() {
60     Entry<K, V> entryWithNull = entry(k3(), null);
61     runEntryWithNullTest(entryWithNull);
62   }
63 
64   private void runEntryWithNullTest(Entry<K, V> entryWithNull) {
65     Collection<Entry<K, V>> entries = getSampleEntries(getNumEntries() - 1);
66 
67     entries.add(entryWithNull);
68 
69     int expectedHashCode = 0;
70     for (Entry<K, V> entry : entries) {
71       expectedHashCode += hash(entry);
72     }
73 
74     resetContainer(getSubjectGenerator().create(entries.toArray()));
75     assertEquals(
76         "A Map's hashCode() should be the sum of those of its entries (where "
77             + "a null element in an entry counts as having a hash of zero).",
78         expectedHashCode,
79         getMap().hashCode());
80   }
81 
82   private static int hash(Entry<?, ?> e) {
83     return (e.getKey() == null ? 0 : e.getKey().hashCode())
84         ^ (e.getValue() == null ? 0 : e.getValue().hashCode());
85   }
86 }