001/*
002 * Copyright (C) 2008 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.testers;
018
019import static com.google.common.collect.testing.features.CollectionFeature.KNOWN_ORDER;
020import static com.google.common.collect.testing.features.CollectionSize.ONE;
021import static com.google.common.collect.testing.features.CollectionSize.SEVERAL;
022import static com.google.common.collect.testing.features.CollectionSize.ZERO;
023
024import com.google.common.annotations.GwtCompatible;
025import com.google.common.collect.testing.features.CollectionFeature;
026import com.google.common.collect.testing.features.CollectionSize;
027
028/**
029 * A generic JUnit test which tests {@code peek()} operations on a queue. Can't be invoked directly;
030 * please see {@link com.google.common.collect.testing.CollectionTestSuiteBuilder}.
031 *
032 * @author Jared Levy
033 */
034@GwtCompatible
035public class QueuePeekTester<E> extends AbstractQueueTester<E> {
036  @CollectionSize.Require(ZERO)
037  public void testPeek_empty() {
038    assertNull("emptyQueue.peek() should return null", getQueue().peek());
039    expectUnchanged();
040  }
041
042  @CollectionSize.Require(ONE)
043  public void testPeek_size1() {
044    assertEquals("size1Queue.peek() should return first element", e0(), getQueue().peek());
045    expectUnchanged();
046  }
047
048  @CollectionFeature.Require(KNOWN_ORDER)
049  @CollectionSize.Require(SEVERAL)
050  public void testPeek_sizeMany() {
051    assertEquals("sizeManyQueue.peek() should return first element", e0(), getQueue().peek());
052    expectUnchanged();
053  }
054}