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 com.google.common.annotations.GwtCompatible; 020import com.google.common.annotations.GwtIncompatible; 021import com.google.common.collect.testing.Helpers; 022import java.lang.reflect.Method; 023import org.junit.Ignore; 024 025/** 026 * Tests {@link java.util.List#hashCode}. 027 * 028 * @author George van den Driessche 029 */ 030@GwtCompatible(emulated = true) 031@Ignore // Affects only Android test runner, which respects JUnit 4 annotations on JUnit 3 tests. 032public class ListHashCodeTester<E> extends AbstractListTester<E> { 033 public void testHashCode() { 034 int expectedHashCode = 1; 035 for (E element : getOrderedElements()) { 036 expectedHashCode = 31 * expectedHashCode + ((element == null) ? 0 : element.hashCode()); 037 } 038 assertEquals( 039 "A List's hashCode() should be computed from those of its elements.", 040 expectedHashCode, 041 getList().hashCode()); 042 } 043 044 /** 045 * Returns the {@link Method} instance for {@link #testHashCode()} so that list tests on 046 * unhashable objects can suppress it with {@code FeatureSpecificTestSuiteBuilder.suppressing()}. 047 */ 048 @GwtIncompatible // reflection 049 public static Method getHashCodeMethod() { 050 return Helpers.getMethod(ListHashCodeTester.class, "testHashCode"); 051 } 052}