/*
    * Copyright (C) 2008 The Guava Authors
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    * http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.google.common.collect.testing.testers;
  
  import static com.google.common.collect.testing.features.CollectionFeature.KNOWN_ORDER;
  import static com.google.common.collect.testing.features.CollectionSize.ONE;
  import static com.google.common.collect.testing.features.CollectionSize.SEVERAL;
  import static com.google.common.collect.testing.features.CollectionSize.ZERO;
  
  import com.google.common.annotations.GwtCompatible;
  import com.google.common.collect.testing.features.CollectionFeature;
  import com.google.common.collect.testing.features.CollectionSize;
  
  /**
   * A generic JUnit test which tests {@code peek()} operations on a queue.
   * Can't be invoked directly; please see
   * {@link com.google.common.collect.testing.CollectionTestSuiteBuilder}.
   *
   * @author Jared Levy
   */
  @GwtCompatible
  public class QueuePeekTester<E> extends AbstractQueueTester<E> {
    @CollectionSize.Require(ZERO)
    public void testPeek_empty() {
      assertNull("emptyQueue.peek() should return null", getQueue().peek());
      expectUnchanged();
    }
  
    @CollectionSize.Require(ONE)
    public void testPeek_size1() {
      assertEquals("size1Queue.peek() should return first element",
          samples.e0, getQueue().peek());
      expectUnchanged();
    }
  
    @CollectionFeature.Require(KNOWN_ORDER)
    @CollectionSize.Require(SEVERAL)
    public void testPeek_sizeMany() {
      assertEquals("sizeManyQueue.peek() should return first element",
          samples.e0, getQueue().peek());
      expectUnchanged();
    }
  }