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.jspecify.annotations.NullMarked;
023import org.jspecify.annotations.Nullable;
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@NullMarked
033public abstract class AbstractCollectionTester<E extends @Nullable Object>
034    extends AbstractContainerTester<Collection<E>, E> {
035
036  // TODO: replace this with an accessor.
037  protected Collection<E> collection;
038
039  @Override
040  protected Collection<E> actualContents() {
041    return collection;
042  }
043
044  // TODO: dispose of this once collection is encapsulated.
045  @Override
046  @CanIgnoreReturnValue
047  protected Collection<E> resetContainer(Collection<E> newContents) {
048    collection = super.resetContainer(newContents);
049    return collection;
050  }
051
052  /**
053   * @see AbstractContainerTester#resetContainer()
054   */
055  protected void resetCollection() {
056    resetContainer();
057  }
058
059  /**
060   * @return an array of the proper size with {@code null} inserted into the middle element.
061   */
062  protected E[] createArrayWithNullElement() {
063    E[] array = createSamplesArray();
064    array[getNullLocation()] = null;
065    return array;
066  }
067
068  protected void initCollectionWithNullElement() {
069    E[] array = createArrayWithNullElement();
070    resetContainer(getSubjectGenerator().create(array));
071  }
072
073  /**
074   * Equivalent to {@link #expectMissing(Object[]) expectMissing}{@code (null)} except that the call
075   * to {@code contains(null)} is permitted to throw a {@code NullPointerException}.
076   *
077   * @param message message to use upon assertion failure
078   */
079  protected void expectNullMissingWhenNullUnsupported(String message) {
080    try {
081      assertFalse(message, actualContents().contains(null));
082    } catch (NullPointerException tolerated) {
083      // Tolerated
084    }
085  }
086}