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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.CollectionFeature.ALLOWS_NULL_QUERIES;
     20 import static com.google.common.collect.testing.features.CollectionFeature.ALLOWS_NULL_VALUES;
     21 import static com.google.common.collect.testing.features.CollectionFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION;
     22 import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_REMOVE;
     23 import static com.google.common.collect.testing.features.CollectionSize.SEVERAL;
     24 import static com.google.common.collect.testing.features.CollectionSize.ZERO;
     25 
     26 import com.google.common.annotations.GwtCompatible;
     27 import com.google.common.collect.testing.AbstractCollectionTester;
     28 import com.google.common.collect.testing.WrongType;
     29 import com.google.common.collect.testing.features.CollectionFeature;
     30 import com.google.common.collect.testing.features.CollectionSize;
     31 
     32 import java.util.ConcurrentModificationException;
     33 import java.util.Iterator;
     34 
     35 /**
     36  * A generic JUnit test which tests {@code remove} operations on a collection.
     37  * Can't be invoked directly; please see
     38  * {@link com.google.common.collect.testing.CollectionTestSuiteBuilder}.
     39  *
     40  * @author George van den Driessche
     41  */
     42 @SuppressWarnings("unchecked") // too many "unchecked generic array creations"
     43 @GwtCompatible
     44 public class CollectionRemoveTester<E> extends AbstractCollectionTester<E> {
     45   @CollectionFeature.Require(SUPPORTS_REMOVE)
     46   @CollectionSize.Require(absent = ZERO)
     47   public void testRemove_present() {
     48     int initialSize = collection.size();
     49     assertTrue("remove(present) should return true",
     50         collection.remove(samples.e0));
     51     assertEquals("remove(present) should decrease a collection's size by one.",
     52         initialSize - 1, collection.size());
     53     expectMissing(samples.e0);
     54   }
     55 
     56   @CollectionFeature.Require({SUPPORTS_REMOVE,
     57       FAILS_FAST_ON_CONCURRENT_MODIFICATION})
     58   @CollectionSize.Require(SEVERAL)
     59   public void testRemovePresentConcurrentWithIteration() {
     60     try {
     61       Iterator<E> iterator = collection.iterator();
     62       assertTrue(collection.remove(samples.e0));
     63       iterator.next();
     64       fail("Expected ConcurrentModificationException");
     65     } catch (ConcurrentModificationException expected) {
     66       // success
     67     }
     68   }
     69 
     70   @CollectionFeature.Require(SUPPORTS_REMOVE)
     71   public void testRemove_notPresent() {
     72     assertFalse("remove(notPresent) should return false",
     73         collection.remove(samples.e3));
     74     expectUnchanged();
     75   }
     76 
     77   @CollectionFeature.Require({SUPPORTS_REMOVE, ALLOWS_NULL_VALUES})
     78   @CollectionSize.Require(absent = ZERO)
     79   public void testRemove_nullPresent() {
     80     collection = getSubjectGenerator().create(createArrayWithNullElement());
     81 
     82     int initialSize = collection.size();
     83     assertTrue("remove(null) should return true", collection.remove(null));
     84     assertEquals("remove(present) should decrease a collection's size by one.",
     85         initialSize - 1, collection.size());
     86     expectMissing((E) null);
     87   }
     88 
     89   @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
     90   @CollectionSize.Require(absent = ZERO)
     91   public void testRemove_unsupported() {
     92     try {
     93       collection.remove(samples.e0);
     94       fail("remove(present) should throw UnsupportedOperationException");
     95     } catch (UnsupportedOperationException expected) {
     96     }
     97     expectUnchanged();
     98     assertTrue("remove(present) should not remove the element",
     99         collection.contains(samples.e0));
    100   }
    101 
    102   @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
    103   public void testRemove_unsupportedNotPresent() {
    104     try {
    105       assertFalse("remove(notPresent) should return false or throw "
    106           + "UnsupportedOperationException",
    107           collection.remove(samples.e3));
    108     } catch (UnsupportedOperationException tolerated) {
    109     }
    110     expectUnchanged();
    111     expectMissing(samples.e3);
    112   }
    113 
    114   @CollectionFeature.Require(
    115       value = SUPPORTS_REMOVE,
    116       absent = ALLOWS_NULL_QUERIES)
    117   public void testRemove_nullNotSupported() {
    118     try {
    119       assertFalse("remove(null) should return false or throw "
    120           + "NullPointerException",
    121           collection.remove(null));
    122     } catch (NullPointerException tolerated) {
    123     }
    124     expectUnchanged();
    125   }
    126 
    127   @CollectionFeature.Require({SUPPORTS_REMOVE, ALLOWS_NULL_QUERIES})
    128   public void testRemove_nullAllowed() {
    129     assertFalse("remove(null) should return false", collection.remove(null));
    130     expectUnchanged();
    131   }
    132 
    133   @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
    134   @CollectionSize.Require(absent = ZERO)
    135   public void testIteratorRemove_unsupported() {
    136     Iterator<E> iterator = collection.iterator();
    137     iterator.next();
    138     try {
    139       iterator.remove();
    140       fail("iterator.remove() should throw UnsupportedOperationException");
    141     } catch (UnsupportedOperationException expected) {
    142     }
    143     expectUnchanged();
    144     assertTrue(collection.contains(samples.e0));
    145   }
    146 
    147   @CollectionFeature.Require(SUPPORTS_REMOVE)
    148   public void testRemove_wrongType() {
    149     try {
    150       assertFalse(collection.remove(WrongType.VALUE));
    151     } catch (ClassCastException tolerated) {
    152     }
    153     expectUnchanged();
    154   }
    155 }
    156