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      1 /*
      2  * Copyright (C) 2008 The Guava Authors
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  * http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.google.common.collect.testing.testers;
     18 
     19 import static com.google.common.collect.testing.features.CollectionSize.SEVERAL;
     20 import static com.google.common.collect.testing.features.CollectionSize.ZERO;
     21 import static com.google.common.collect.testing.features.MapFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION;
     22 import static com.google.common.collect.testing.features.MapFeature.SUPPORTS_REMOVE;
     23 
     24 import com.google.common.annotations.GwtCompatible;
     25 import com.google.common.collect.testing.AbstractMapTester;
     26 import com.google.common.collect.testing.features.CollectionSize;
     27 import com.google.common.collect.testing.features.MapFeature;
     28 
     29 import java.util.ConcurrentModificationException;
     30 import java.util.Iterator;
     31 import java.util.Map.Entry;
     32 
     33 /**
     34  * A generic JUnit test which tests {@code clear()} operations on a map.
     35  * Can't be invoked directly; please see
     36  * {@link com.google.common.collect.testing.MapTestSuiteBuilder}.
     37  *
     38  * @author George van den Driessche
     39  * @author Chris Povirk
     40  */
     41 @GwtCompatible
     42 public class MapClearTester<K, V> extends AbstractMapTester<K, V> {
     43   @MapFeature.Require(SUPPORTS_REMOVE)
     44   public void testClear() {
     45     getMap().clear();
     46     assertTrue("After clear(), a map should be empty.",
     47         getMap().isEmpty());
     48   }
     49 
     50   @MapFeature.Require({FAILS_FAST_ON_CONCURRENT_MODIFICATION,
     51       SUPPORTS_REMOVE})
     52   @CollectionSize.Require(SEVERAL)
     53   public void testClearConcurrentWithEntrySetIteration() {
     54     try {
     55       Iterator<Entry<K, V>> iterator = getMap().entrySet().iterator();
     56       getMap().clear();
     57       iterator.next();
     58       fail("Expected ConcurrentModificationException");
     59     } catch (ConcurrentModificationException expected) {
     60       // success
     61     }
     62   }
     63 
     64   @MapFeature.Require({FAILS_FAST_ON_CONCURRENT_MODIFICATION,
     65       SUPPORTS_REMOVE})
     66   @CollectionSize.Require(SEVERAL)
     67   public void testClearConcurrentWithKeySetIteration() {
     68     try {
     69       Iterator<K> iterator = getMap().keySet().iterator();
     70       getMap().clear();
     71       iterator.next();
     72       fail("Expected ConcurrentModificationException");
     73     } catch (ConcurrentModificationException expected) {
     74       // success
     75     }
     76   }
     77 
     78   @MapFeature.Require({FAILS_FAST_ON_CONCURRENT_MODIFICATION,
     79       SUPPORTS_REMOVE})
     80   @CollectionSize.Require(SEVERAL)
     81   public void testClearConcurrentWithValuesIteration() {
     82     try {
     83       Iterator<V> iterator = getMap().values().iterator();
     84       getMap().clear();
     85       iterator.next();
     86       fail("Expected ConcurrentModificationException");
     87     } catch (ConcurrentModificationException expected) {
     88       // success
     89     }
     90   }
     91 
     92   @MapFeature.Require(absent = SUPPORTS_REMOVE)
     93   @CollectionSize.Require(absent = ZERO)
     94   public void testClear_unsupported() {
     95     try {
     96       getMap().clear();
     97       fail("clear() should throw UnsupportedOperation if a map does "
     98           + "not support it and is not empty.");
     99     } catch (UnsupportedOperationException expected) {
    100     }
    101     expectUnchanged();
    102   }
    103 
    104   @MapFeature.Require(absent = SUPPORTS_REMOVE)
    105   @CollectionSize.Require(ZERO)
    106   public void testClear_unsupportedByEmptyCollection() {
    107     try {
    108       getMap().clear();
    109     } catch (UnsupportedOperationException tolerated) {
    110     }
    111     expectUnchanged();
    112   }
    113 }
    114