com.google.common.collect.testing.testers.ListHashCodeTester Maven / Gradle / Ivy
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/*
* Copyright (C) 2008 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.common.collect.testing.testers;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.collect.testing.Helpers;
import java.lang.reflect.Method;
/**
* Tests {@link java.util.List#hashCode}.
*
* This class is GWT compatible.
*
* @author George van den Driessche
*/
@GwtCompatible(emulated = true)
public class ListHashCodeTester extends AbstractListTester {
public void testHashCode() {
int expectedHashCode = 1;
for (E element : getOrderedElements()) {
expectedHashCode = 31 * expectedHashCode +
((element == null) ? 0 : element.hashCode());
}
assertEquals(
"A List's hashCode() should be computed from those of its elements.",
expectedHashCode, getList().hashCode());
}
/**
* Returns the {@link Method} instance for {@link #testHashCode()} so that
* list tests on unhashable objects can suppress it with
* {@code FeatureSpecificTestSuiteBuilder.suppressing()}.
*/
@GwtIncompatible("reflection")
public static Method getHashCodeMethod() {
return Helpers.getMethod(ListHashCodeTester.class, "testHashCode");
}
}