/* * Copyright (C) 2011 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.testing; import static com.google.common.base.Preconditions.checkNotNull; import static junit.framework.Assert.assertEquals; import static junit.framework.Assert.assertTrue; import com.google.common.annotations.Beta; import com.google.common.annotations.GwtCompatible; import com.google.common.base.Equivalence; import com.google.common.collect.ImmutableList; import com.google.common.collect.Lists; import com.google.common.testing.RelationshipTester.ItemReporter; import java.util.List; /** * Tester for {@link Equivalence} relationships between groups of objects. * *

* To use, create a new {@link EquivalenceTester} and add equivalence groups * where each group contains objects that are supposed to be equal to each * other. Objects of different groups are expected to be unequal. For example: * *

 * {@code
 * EquivalenceTester.of(someStringEquivalence)
 *     .addEquivalenceGroup("hello", "h" + "ello")
 *     .addEquivalenceGroup("world", "wor" + "ld")
 *     .test();
 * }
 * 
* *

* Note that testing {@link Object#equals(Object)} is more simply done using * the {@link EqualsTester}. It includes an extra test against an instance of an * arbitrary class without having to explicitly add another equivalence group. * * @author Gregory Kick * @since 10.0 * * TODO(gak): turn this into a test suite so that each test can fail * independently */ @Beta @GwtCompatible public final class EquivalenceTester { private static final int REPETITIONS = 3; private final Equivalence equivalence; private final RelationshipTester delegate; private final List items = Lists.newArrayList(); private EquivalenceTester(Equivalence equivalence) { this.equivalence = checkNotNull(equivalence); this.delegate = new RelationshipTester( equivalence, "equivalent", "hash", new ItemReporter()); } public static EquivalenceTester of(Equivalence equivalence) { return new EquivalenceTester(equivalence); } /** * Adds a group of objects that are supposed to be equivalent to each other * and not equivalent to objects in any other equivalence group added to this * tester. */ public EquivalenceTester addEquivalenceGroup(T first, T... rest) { addEquivalenceGroup(Lists.asList(first, rest)); return this; } public EquivalenceTester addEquivalenceGroup(Iterable group) { delegate.addRelatedGroup(group); items.addAll(ImmutableList.copyOf(group)); return this; } /** Run tests on equivalence methods, throwing a failure on an invalid test */ public EquivalenceTester test() { for (int run = 0; run < REPETITIONS; run++) { testItems(); delegate.test(); } return this; } private void testItems() { for (T item : items) { /* * TODO(cpovirk): consider no longer running these equivalent() tests on every Equivalence, * since the Equivalence base type now implements this logic itself */ assertTrue(item + " must be inequivalent to null", !equivalence.equivalent(item, null)); assertTrue("null must be inequivalent to " + item, !equivalence.equivalent(null, item)); assertTrue(item + " must be equivalent to itself", equivalence.equivalent(item, item)); assertEquals("the hash of " + item + " must be consistent", equivalence.hash(item), equivalence.hash(item)); } } }