com.google.common.collect.testing.testers.SetHashCodeTester 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 static com.google.common.collect.testing.features.CollectionFeature.ALLOWS_NULL_VALUES;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.collect.testing.Helpers;
import com.google.common.collect.testing.features.CollectionFeature;
import com.google.common.collect.testing.features.CollectionSize;
import java.lang.reflect.Method;
import java.util.Collection;
/**
* Tests {@link java.util.Set#hashCode}.
*
* This class is GWT compatible.
*
* @author George van den Driessche
*/
@GwtCompatible(emulated = true)
public class SetHashCodeTester extends AbstractSetTester {
public void testHashCode() {
int expectedHashCode = 0;
for (E element : getSampleElements()) {
expectedHashCode += ((element == null) ? 0 : element.hashCode());
}
assertEquals(
"A Set's hashCode() should be the sum of those of its elements.",
expectedHashCode, getSet().hashCode());
}
@CollectionSize.Require(absent = CollectionSize.ZERO)
@CollectionFeature.Require(ALLOWS_NULL_VALUES)
public void testHashCode_containingNull() {
Collection elements = getSampleElements(getNumElements() - 1);
int expectedHashCode = 0;
for (E element : elements) {
expectedHashCode += ((element == null) ? 0 : element.hashCode());
}
elements.add(null);
collection = getSubjectGenerator().create(elements.toArray());
assertEquals(
"A Set's hashCode() should be the sum of those of its elements (with "
+ "a null element counting as having a hash of zero).",
expectedHashCode, getSet().hashCode());
}
/**
* Returns the {@link Method} instances for the test methods in this class
* which call {@code hashCode()} on the set values so that set tests on
* unhashable objects can suppress it with
* {@code FeatureSpecificTestSuiteBuilder.suppressing()}.
*/
@GwtIncompatible("reflection")
public static Method[] getHashCodeMethods() {
return new Method[]{
Helpers.getMethod(SetHashCodeTester.class, "testHashCode"),
Helpers.getMethod(SetHashCodeTester.class, "testHashCode_containingNull") };
}
}