Coverage Summary for Class: SetHashCodeTester (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.CollectionFeature.ALLOWS_NULL_VALUES;
20 
21 import com.google.common.annotations.GwtCompatible;
22 import com.google.common.annotations.GwtIncompatible;
23 import com.google.common.collect.testing.Helpers;
24 import com.google.common.collect.testing.features.CollectionFeature;
25 import com.google.common.collect.testing.features.CollectionSize;
26 import java.lang.reflect.Method;
27 import java.util.Collection;
28 import org.junit.Ignore;
29 
30 /**
31  * Tests {@link java.util.Set#hashCode}.
32  *
33  * @author George van den Driessche
34  */
35 @GwtCompatible(emulated = true)
36 @Ignore // Affects only Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
37 public class SetHashCodeTester<E> extends AbstractSetTester<E> {
38   public void testHashCode() {
39     int expectedHashCode = 0;
40     for (E element : getSampleElements()) {
41       expectedHashCode += ((element == null) ? 0 : element.hashCode());
42     }
43     assertEquals(
44         "A Set's hashCode() should be the sum of those of its elements.",
45         expectedHashCode,
46         getSet().hashCode());
47   }
48 
49   @CollectionSize.Require(absent = CollectionSize.ZERO)
50   @CollectionFeature.Require(ALLOWS_NULL_VALUES)
51   public void testHashCode_containingNull() {
52     Collection<E> elements = getSampleElements(getNumElements() - 1);
53     int expectedHashCode = 0;
54     for (E element : elements) {
55       expectedHashCode += ((element == null) ? 0 : element.hashCode());
56     }
57 
58     elements.add(null);
59     collection = getSubjectGenerator().create(elements.toArray());
60     assertEquals(
61         "A Set's hashCode() should be the sum of those of its elements (with "
62             + "a null element counting as having a hash of zero).",
63         expectedHashCode,
64         getSet().hashCode());
65   }
66 
67   /**
68    * Returns the {@link Method} instances for the test methods in this class which call {@code
69    * hashCode()} on the set values so that set tests on unhashable objects can suppress it with
70    * {@code FeatureSpecificTestSuiteBuilder.suppressing()}.
71    */
72   @GwtIncompatible // reflection
73   public static Method[] getHashCodeMethods() {
74     return new Method[] {
75       Helpers.getMethod(SetHashCodeTester.class, "testHashCode"),
76       Helpers.getMethod(SetHashCodeTester.class, "testHashCode_containingNull")
77     };
78   }
79 }