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
17package com.google.common.collect.testing;
18
19import com.google.common.annotations.GwtCompatible;
20
21import 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
31public 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