1 /*
2  * Copyright (C) 2007 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;
18 
19 import com.google.common.annotations.GwtCompatible;
20 
21 import java.util.Collection;
22 
23 /**
24  * Base class for collection testers.
25  *
26  * @param <E> the element type of the collection to be tested.
27  *
28  * @author Kevin Bourrillion
29  */
30 @GwtCompatible
31 public abstract class AbstractCollectionTester<E>
32     extends AbstractContainerTester<Collection<E>, E> {
33 
34   // TODO: replace this with an accessor.
35   protected Collection<E> collection;
36 
37   @Override protected Collection<E> actualContents() {
38     return collection;
39   }
40 
41   // TODO: dispose of this once collection is encapsulated.
42   @Override protected Collection<E> resetContainer(Collection<E> newContents) {
43     collection = super.resetContainer(newContents);
44     return collection;
45   }
46 
47   /** @see AbstractContainerTester#resetContainer() */
48   protected void resetCollection() {
49     resetContainer();
50   }
51 
52   /**
53    * @return an array of the proper size with {@code null} inserted into the
54    * middle element.
55    */
56   protected E[] createArrayWithNullElement() {
57     E[] array = createSamplesArray();
58     array[getNullLocation()] = null;
59     return array;
60   }
61 
62   protected void initCollectionWithNullElement() {
63     E[] array = createArrayWithNullElement();
64     resetContainer(getSubjectGenerator().create(array));
65   }
66 
67   /**
68    * Equivalent to {@link #expectMissing(Object[]) expectMissing}{@code (null)}
69    * except that the call to {@code contains(null)} is permitted to throw a
70    * {@code NullPointerException}.
71    *
72    * @param message message to use upon assertion failure
73    */
74   protected void expectNullMissingWhenNullUnsupported(String message) {
75     try {
76       assertFalse(message, actualContents().contains(null));
77     } catch (NullPointerException tolerated) {
78       // Tolerated
79     }
80   }
81 }
82