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> { testHashCode()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) testHashCode_containingNullKey()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) testHashCode_containingNullValue()59 public void testHashCode_containingNullValue() { 60 Entry<K, V> entryWithNull = entry(k3(), null); 61 runEntryWithNullTest(entryWithNull); 62 } 63 runEntryWithNullTest(Entry<K, V> entryWithNull)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 hash(Entry<?, ?> e)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 } 87