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.FAILS_FAST_ON_CONCURRENT_MODIFICATION;
020import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_REMOVE;
021import static com.google.common.collect.testing.features.CollectionSize.SEVERAL;
022import static com.google.common.collect.testing.features.CollectionSize.ZERO;
023import static org.junit.Assert.assertThrows;
024
025import com.google.common.annotations.GwtCompatible;
026import com.google.common.collect.testing.AbstractCollectionTester;
027import com.google.common.collect.testing.features.CollectionFeature;
028import com.google.common.collect.testing.features.CollectionSize;
029import java.util.ConcurrentModificationException;
030import java.util.Iterator;
031
032/**
033 * A generic JUnit test which tests {@code clear()} operations on a collection. Can't be invoked
034 * directly; please see {@link com.google.common.collect.testing.CollectionTestSuiteBuilder}.
035 *
036 * @author George van den Driessche
037 */
038@GwtCompatible
039public class CollectionClearTester<E> extends AbstractCollectionTester<E> {
040  @CollectionFeature.Require(SUPPORTS_REMOVE)
041  public void testClear() {
042    collection.clear();
043    assertTrue("After clear(), a collection should be empty.", collection.isEmpty());
044    assertEquals(0, collection.size());
045    assertFalse(collection.iterator().hasNext());
046  }
047
048  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
049  @CollectionSize.Require(absent = ZERO)
050  public void testClear_unsupported() {
051    assertThrows(UnsupportedOperationException.class, () -> collection.clear());
052    expectUnchanged();
053  }
054
055  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
056  @CollectionSize.Require(ZERO)
057  public void testClear_unsupportedByEmptyCollection() {
058    try {
059      collection.clear();
060    } catch (UnsupportedOperationException tolerated) {
061    }
062    expectUnchanged();
063  }
064
065  @CollectionFeature.Require({SUPPORTS_REMOVE, FAILS_FAST_ON_CONCURRENT_MODIFICATION})
066  @CollectionSize.Require(SEVERAL)
067  public void testClearConcurrentWithIteration() {
068    Iterator<E> iterator = collection.iterator();
069    collection.clear();
070    assertThrows(ConcurrentModificationException.class, iterator::next);
071  }
072}