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;
023
024import com.google.common.annotations.GwtCompatible;
025import com.google.common.collect.testing.AbstractCollectionTester;
026import com.google.common.collect.testing.features.CollectionFeature;
027import com.google.common.collect.testing.features.CollectionSize;
028import java.util.ConcurrentModificationException;
029import java.util.Iterator;
030
031/**
032 * A generic JUnit test which tests {@code clear()} operations on a collection. Can't be invoked
033 * directly; please see {@link com.google.common.collect.testing.CollectionTestSuiteBuilder}.
034 *
035 * @author George van den Driessche
036 */
037@GwtCompatible
038public class CollectionClearTester<E> extends AbstractCollectionTester<E> {
039  @CollectionFeature.Require(SUPPORTS_REMOVE)
040  public void testClear() {
041    collection.clear();
042    assertTrue("After clear(), a collection should be empty.", collection.isEmpty());
043    assertEquals(0, collection.size());
044    assertFalse(collection.iterator().hasNext());
045  }
046
047  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
048  @CollectionSize.Require(absent = ZERO)
049  public void testClear_unsupported() {
050    try {
051      collection.clear();
052      fail(
053          "clear() should throw UnsupportedOperation if a collection does "
054              + "not support it and is not empty.");
055    } catch (UnsupportedOperationException expected) {
056    }
057    expectUnchanged();
058  }
059
060  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
061  @CollectionSize.Require(ZERO)
062  public void testClear_unsupportedByEmptyCollection() {
063    try {
064      collection.clear();
065    } catch (UnsupportedOperationException tolerated) {
066    }
067    expectUnchanged();
068  }
069
070  @CollectionFeature.Require({SUPPORTS_REMOVE, FAILS_FAST_ON_CONCURRENT_MODIFICATION})
071  @CollectionSize.Require(SEVERAL)
072  public void testClearConcurrentWithIteration() {
073    try {
074      Iterator<E> iterator = collection.iterator();
075      collection.clear();
076      iterator.next();
077      /*
078       * We prefer for iterators to fail immediately on hasNext, but ArrayList
079       * and LinkedList will notably return true on hasNext here!
080       */
081      fail("Expected ConcurrentModificationException");
082    } catch (ConcurrentModificationException expected) {
083      // success
084    }
085  }
086}