com.google.common.collect.testing.features.CollectionSize.java Source code

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Here is the source code for com.google.common.collect.testing.features.CollectionSize.java

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/*
 * 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.features;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.Helpers;

import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.Collection;
import java.util.Collections;
import java.util.Set;

/**
 * When describing the features of the collection produced by a given generator
 * (i.e. in a call to {@link
 * com.google.common.collect.testing.FeatureSpecificTestSuiteBuilder#withFeatures(Feature...)}),
 * this annotation specifies each of the different sizes for which a test suite
 * should be built. (In a typical case, the features should include {@link
 * CollectionSize#ANY}.) These semantics are thus a little different
 * from those of other Collection-related features such as {@link
 * CollectionFeature} or {@link SetFeature}.
 * <p>
 * However, when {@link CollectionSize.Require} is used to annotate a test it
 * behaves normally (i.e. it requires the collection instance under test to be
 * a certain size for the test to run). Note that this means a test should not
 * require more than one CollectionSize, since a particular collection instance
 * can only be one size at once.
 *
 * @author George van den Driessche
 */
// Enum values use constructors with generic varargs.
@SuppressWarnings("unchecked")
@GwtCompatible
public enum CollectionSize implements Feature<Collection>, Comparable<CollectionSize> {
    /** Test an empty collection. */
    ZERO(0),
    /** Test a one-element collection. */
    ONE(1),
    /** Test a three-element collection. */
    SEVERAL(3),
    /*
     * TODO: add VERY_LARGE, noting that we currently assume that the fourth
     * sample element is not in any collection
     */

    ANY(ZERO, ONE, SEVERAL);

    private final Set<Feature<? super Collection>> implied;
    private final Integer numElements;

    CollectionSize(int numElements) {
        this.implied = Collections.emptySet();
        this.numElements = numElements;
    }

    CollectionSize(Feature<? super Collection>... implied) {
        // Keep the order here, so that PerCollectionSizeTestSuiteBuilder
        // gives a predictable order of test suites.
        this.implied = Helpers.copyToSet(implied);
        this.numElements = null;
    }

    @Override
    public Set<Feature<? super Collection>> getImpliedFeatures() {
        return implied;
    }

    public int getNumElements() {
        if (numElements == null) {
            throw new IllegalStateException("A compound CollectionSize doesn't specify a number of elements.");
        }
        return numElements;
    }

    @Retention(RetentionPolicy.RUNTIME)
    @Inherited
    @TesterAnnotation
    public @interface Require {
        CollectionSize[] value() default {};

        CollectionSize[] absent() default {};
    }
}