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.features;
18  
19  import com.google.common.annotations.GwtCompatible;
20  import com.google.common.collect.testing.Helpers;
21  
22  import java.lang.annotation.Inherited;
23  import java.lang.annotation.Retention;
24  import java.lang.annotation.RetentionPolicy;
25  import java.util.Collection;
26  import java.util.Collections;
27  import java.util.Set;
28  
29  /**
30   * When describing the features of the collection produced by a given generator
31   * (i.e. in a call to {@link
32   * com.google.common.collect.testing.FeatureSpecificTestSuiteBuilder#withFeatures(Feature...)}),
33   * this annotation specifies each of the different sizes for which a test suite
34   * should be built. (In a typical case, the features should include {@link
35   * CollectionSize#ANY}.) These semantics are thus a little different
36   * from those of other Collection-related features such as {@link
37   * CollectionFeature} or {@link SetFeature}.
38   * <p>
39   * However, when {@link CollectionSize.Require} is used to annotate a test it
40   * behaves normally (i.e. it requires the collection instance under test to be
41   * a certain size for the test to run). Note that this means a test should not
42   * require more than one CollectionSize, since a particular collection instance
43   * can only be one size at once.
44   *
45   * @author George van den Driessche
46   */
47  // Enum values use constructors with generic varargs.
48  @SuppressWarnings("unchecked")
49  @GwtCompatible
50  public enum CollectionSize implements Feature<Collection>,
51      Comparable<CollectionSize> {
52    /** Test an empty collection. */
53    ZERO(0),
54    /** Test a one-element collection. */
55    ONE(1),
56    /** Test a three-element collection. */
57    SEVERAL(3),
58    /*
59     * TODO: add VERY_LARGE, noting that we currently assume that the fourth
60     * sample element is not in any collection
61     */
62  
63    ANY(
64        ZERO,
65        ONE,
66        SEVERAL
67    );
68  
69    private final Set<Feature<? super Collection>> implied;
70    private final Integer numElements;
71  
72    CollectionSize(int numElements) {
73      this.implied = Collections.emptySet();
74      this.numElements = numElements;
75    }
76  
77    CollectionSize(Feature<? super Collection> ... implied) {
78      // Keep the order here, so that PerCollectionSizeTestSuiteBuilder
79      // gives a predictable order of test suites.
80      this.implied = Helpers.copyToSet(implied);
81      this.numElements = null;
82    }
83  
84    @Override
85    public Set<Feature<? super Collection>> getImpliedFeatures() {
86      return implied;
87    }
88  
89    public int getNumElements() {
90      if (numElements == null) {
91        throw new IllegalStateException(
92            "A compound CollectionSize doesn't specify a number of elements.");
93      }
94      return numElements;
95    }
96  
97    @Retention(RetentionPolicy.RUNTIME)
98    @Inherited
99    @TesterAnnotation
100   public @interface Require {
101     CollectionSize[] value() default {};
102     CollectionSize[] absent() default {};
103   }
104 }