1   /*
2    * Copyright (C) 2008 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  
17  package com.google.common.collect.testing.testers;
18  
19  import com.google.common.annotations.GwtCompatible;
20  
21  /**
22   * Tests {@link java.util.List#hashCode}.
23   *
24   * @author George van den Driessche
25   */
26  @GwtCompatible(emulated = true)
27  public class ListHashCodeTester<E> extends AbstractListTester<E> {
28    public void testHashCode() {
29      int expectedHashCode = 1;
30      for (E element : getOrderedElements()) {
31        expectedHashCode = 31 * expectedHashCode +
32            ((element == null) ? 0 : element.hashCode());
33      }
34      assertEquals(
35          "A List's hashCode() should be computed from those of its elements.",
36          expectedHashCode, getList().hashCode());
37    }
38  }
39