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; 030import org.junit.Ignore; 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 039@Ignore // Affects only Android test runner, which respects JUnit 4 annotations on JUnit 3 tests. 040public class CollectionClearTester<E> extends AbstractCollectionTester<E> { 041 @CollectionFeature.Require(SUPPORTS_REMOVE) 042 public void testClear() { 043 collection.clear(); 044 assertTrue("After clear(), a collection should be empty.", collection.isEmpty()); 045 assertEquals(0, collection.size()); 046 assertFalse(collection.iterator().hasNext()); 047 } 048 049 @CollectionFeature.Require(absent = SUPPORTS_REMOVE) 050 @CollectionSize.Require(absent = ZERO) 051 public void testClear_unsupported() { 052 try { 053 collection.clear(); 054 fail( 055 "clear() should throw UnsupportedOperation if a collection does " 056 + "not support it and is not empty."); 057 } catch (UnsupportedOperationException expected) { 058 } 059 expectUnchanged(); 060 } 061 062 @CollectionFeature.Require(absent = SUPPORTS_REMOVE) 063 @CollectionSize.Require(ZERO) 064 public void testClear_unsupportedByEmptyCollection() { 065 try { 066 collection.clear(); 067 } catch (UnsupportedOperationException tolerated) { 068 } 069 expectUnchanged(); 070 } 071 072 @CollectionFeature.Require({SUPPORTS_REMOVE, FAILS_FAST_ON_CONCURRENT_MODIFICATION}) 073 @CollectionSize.Require(SEVERAL) 074 public void testClearConcurrentWithIteration() { 075 try { 076 Iterator<E> iterator = collection.iterator(); 077 collection.clear(); 078 iterator.next(); 079 /* 080 * We prefer for iterators to fail immediately on hasNext, but ArrayList 081 * and LinkedList will notably return true on hasNext here! 082 */ 083 fail("Expected ConcurrentModificationException"); 084 } catch (ConcurrentModificationException expected) { 085 // success 086 } 087 } 088}