001/* 002 * Copyright (C) 2008 The Guava Authors 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * http://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package com.google.common.collect.testing.testers; 018 019import static com.google.common.collect.testing.features.CollectionFeature.ALLOWS_NULL_VALUES; 020 021import com.google.common.annotations.GwtCompatible; 022import com.google.common.annotations.GwtIncompatible; 023import com.google.common.collect.testing.Helpers; 024import com.google.common.collect.testing.features.CollectionFeature; 025import com.google.common.collect.testing.features.CollectionSize; 026import java.lang.reflect.Method; 027import java.util.Collection; 028import org.junit.Ignore; 029 030/** 031 * Tests {@link java.util.Set#hashCode}. 032 * 033 * @author George van den Driessche 034 */ 035@GwtCompatible(emulated = true) 036@Ignore // Affects only Android test runner, which respects JUnit 4 annotations on JUnit 3 tests. 037public class SetHashCodeTester<E> extends AbstractSetTester<E> { 038 public void testHashCode() { 039 int expectedHashCode = 0; 040 for (E element : getSampleElements()) { 041 expectedHashCode += ((element == null) ? 0 : element.hashCode()); 042 } 043 assertEquals( 044 "A Set's hashCode() should be the sum of those of its elements.", 045 expectedHashCode, 046 getSet().hashCode()); 047 } 048 049 @CollectionSize.Require(absent = CollectionSize.ZERO) 050 @CollectionFeature.Require(ALLOWS_NULL_VALUES) 051 public void testHashCode_containingNull() { 052 Collection<E> elements = getSampleElements(getNumElements() - 1); 053 int expectedHashCode = 0; 054 for (E element : elements) { 055 expectedHashCode += ((element == null) ? 0 : element.hashCode()); 056 } 057 058 elements.add(null); 059 collection = getSubjectGenerator().create(elements.toArray()); 060 assertEquals( 061 "A Set's hashCode() should be the sum of those of its elements (with " 062 + "a null element counting as having a hash of zero).", 063 expectedHashCode, 064 getSet().hashCode()); 065 } 066 067 /** 068 * Returns the {@link Method} instances for the test methods in this class which call {@code 069 * hashCode()} on the set values so that set tests on unhashable objects can suppress it with 070 * {@code FeatureSpecificTestSuiteBuilder.suppressing()}. 071 */ 072 @GwtIncompatible // reflection 073 public static Method[] getHashCodeMethods() { 074 return new Method[] { 075 Helpers.getMethod(SetHashCodeTester.class, "testHashCode"), 076 Helpers.getMethod(SetHashCodeTester.class, "testHashCode_containingNull") 077 }; 078 } 079}