user/test/org/apache/commons/collections/TestSet.java

/*
 * Copyright 1999-2004 The Apache Software Foundation
 *
 * 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 org.apache.commons.collections;

import java.util.Arrays;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

/**
 *  Tests base {@link Set} methods and contracts.<P>
 *
 *  Since {@link Set} doesn't stipulate much new behavior that isn't already
 *  found in {@link Collection}, this class basically just adds tests for
 *  {@link Set#equals()} and {@link Set#hashCode()} along with an updated
 *  {@link #verify()} that ensures elements do not appear more than once in the
 *  set.<P>
 *
 *  To use, subclass and override the {@link #makeEmptySet()}
 *  method.  You may have to override other protected methods if your
 *  set is not modifiable, or if your set restricts what kinds of
 *  elements may be added; see {@link TestCollection} for more details.<P>
 *
 *  @author Paul Jack
 *  @version $Id: TestSet.java,v 1.2.2.1 2004/05/22 12:14:05 scolebourne Exp $
 */
public abstract class TestSet extends TestCollection {


    /**
     *  Constructor.
     *
     *  @param name  name for test
     */
    public TestSet(String name) {
      
    }


    /**
     *  Makes an empty collection by invoking {@link #makeEmptySet()}.  
     *
     *  @return an empty collection
     */
    protected final Collection makeCollection() {
        return makeEmptySet();
    }


    /**
     *  Makes a full collection by invoking {@link #makeFullSet()}.
     *
     *  @return a full collection
     */
    protected final Collection makeFullCollection() {
        return makeFullSet();
    }

    /**
     *  Return the {@link TestCollection#collection} fixture, but cast as a
     *  Set.  
     */
    protected Set getSet() {
        return (Set)collection;
    }

    /**
     *  Returns an empty {@link HashSet} for use in modification testing.
     *
     *  @return a confirmed empty collection
     */
    protected Collection makeConfirmedCollection() {
        return new HashSet();
    }


    /**
     *  Returns a full {@link HashSet} for use in modification testing.
     *
     *  @return a confirmed full collection
     */
    protected Collection makeConfirmedFullCollection() {
        HashSet set = new HashSet();
        set.addAll(Arrays.asList(getFullElements()));
        return set;
    }

    /**
     *  Return the {@link TestCollection#confirmed} fixture, but cast as a 
     *  Set.
     **/
    protected Set getConfirmedSet() {
        return (Set)confirmed;
    }

    /**
     *  Makes an empty set.  The returned set should have no elements.
     *
     *  @return an empty set
     */
    protected abstract Set makeEmptySet();


    /**
     *  Makes a full set by first creating an empty set and then adding
     *  all the elements returned by {@link #getFullElements()}.
     *
     *  Override if your set does not support the add operation.
     *
     *  @return a full set
     */
    protected Set makeFullSet() {
        Set set = makeEmptySet();
        set.addAll(Arrays.asList(getFullElements()));
        return set;
    }


    /**
     *  Tests {@link Set#equals(Object)}.
     */
    public void testSetEquals() {
        resetEmpty();
        assertEquals("Empty sets should be equal", 
                     getSet(), getConfirmedSet());
        verify();

        HashSet set2 = new HashSet();
        set2.add("foo");
        assertTrue("Empty set shouldn't equal nonempty set", 
                   !getSet().equals(set2));

        resetFull();
        assertEquals("Full sets should be equal", getSet(), getConfirmedSet());
        verify();

        set2.clear();
        set2.addAll(Arrays.asList(getOtherElements()));
        assertTrue("Sets with different contents shouldn't be equal", 
                   !getSet().equals(set2));
    }


    /**
     *  Tests {@link Set#hashCode()}.
     */
    public void testSetHashCode() {
        resetEmpty();
        assertEquals("Empty sets have equal hashCodes", 
                     getSet().hashCode(), getConfirmedSet().hashCode());

        resetFull();
        assertEquals("Equal sets have equal hashCodes", 
                     getSet().hashCode(), getConfirmedSet().hashCode());
    }


    /**
     *  Provides additional verifications for sets.
     */
    protected void verify() {
        super.verify();
        assertEquals("Sets should be equal", confirmed, collection);
        assertEquals("Sets should have equal hashCodes", 
                     confirmed.hashCode(), collection.hashCode());
        HashSet set = new HashSet();
        Iterator iterator = collection.iterator();
        while (iterator.hasNext()) {
            assertTrue("Set.iterator should only return unique elements", 
                       set.add(iterator.next()));
        }
    }

}