001/*
002 * Copyright (C) 2007 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;
018
019import com.google.common.annotations.GwtCompatible;
020import com.google.errorprone.annotations.CanIgnoreReturnValue;
021import java.util.Collection;
022import org.checkerframework.checker.nullness.qual.Nullable;
023import org.junit.Ignore;
024
025/**
026 * Base class for collection testers.
027 *
028 * @param <E> the element type of the collection to be tested.
029 * @author Kevin Bourrillion
030 */
031@GwtCompatible
032@Ignore // Affects only Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
033@ElementTypesAreNonnullByDefault
034public abstract class AbstractCollectionTester<E extends @Nullable Object>
035    extends AbstractContainerTester<Collection<E>, E> {
036
037  // TODO: replace this with an accessor.
038  protected Collection<E> collection;
039
040  @Override
041  protected Collection<E> actualContents() {
042    return collection;
043  }
044
045  // TODO: dispose of this once collection is encapsulated.
046  @Override
047  @CanIgnoreReturnValue
048  protected Collection<E> resetContainer(Collection<E> newContents) {
049    collection = super.resetContainer(newContents);
050    return collection;
051  }
052
053  /** @see AbstractContainerTester#resetContainer() */
054  protected void resetCollection() {
055    resetContainer();
056  }
057
058  /** @return an array of the proper size with {@code null} inserted into the middle element. */
059  protected E[] createArrayWithNullElement() {
060    E[] array = createSamplesArray();
061    array[getNullLocation()] = null;
062    return array;
063  }
064
065  protected void initCollectionWithNullElement() {
066    E[] array = createArrayWithNullElement();
067    resetContainer(getSubjectGenerator().create(array));
068  }
069
070  /**
071   * Equivalent to {@link #expectMissing(Object[]) expectMissing}{@code (null)} except that the call
072   * to {@code contains(null)} is permitted to throw a {@code NullPointerException}.
073   *
074   * @param message message to use upon assertion failure
075   */
076  protected void expectNullMissingWhenNullUnsupported(String message) {
077    try {
078      assertFalse(message, actualContents().contains(null));
079    } catch (NullPointerException tolerated) {
080      // Tolerated
081    }
082  }
083}