testsingletonlistiterator.java

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/*
 * 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.iterators;

import junit.framework.*;
import java.util.Iterator;
import java.util.ListIterator;
import java.util.NoSuchElementException;

/**
 * Tests the SingletonListIterator.
 *
 * @author Stephen Colebourne
 * @version $Id: TestSingletonListIterator.java,v 1.1.2.1 2004/05/22 12:14:04 scolebourne Exp $
 */
public class TestSingletonListIterator extends TestIterator {

    private static final Object testValue = "foo";
    
    public static Test suite() {
        return new TestSuite(TestSingletonListIterator.class);
    }
    
    public TestSingletonListIterator(String testName) {
        super(testName);
    }
    
    /**
     * Returns null. SingletonListIterator can never be empty;
     * they always have exactly one element.
     * 
     * @return null
     */
    public Iterator makeEmptyIterator() {
        return null;
    }

    public Iterator makeFullIterator() {
        return new SingletonListIterator( testValue );
    }

    /**
     * Return a new, empty {@link Object} to used for testing.
     */
    public Object makeObject() {
        return makeFullIterator();
    }
    
    /**
     * Whether or not we are testing an iterator that can be
     * empty.  SingletonIterators are never empty;
     * 
     * @return false
     */
    public boolean supportsEmptyIterator() {
        return false;
    }

    public void testIterator() {
        ListIterator iter = (ListIterator) makeObject();
        assertTrue( "Iterator should have next item", iter.hasNext() );
        assertTrue( "Iterator should have no previous item", !iter.hasPrevious() );
        assertEquals( "Iteration next index", 0, iter.nextIndex() );
        assertEquals( "Iteration previous index", -1, iter.previousIndex() );
        
        Object iterValue = iter.next();
        assertEquals( "Iteration value is correct", testValue, iterValue );
        
        assertTrue( "Iterator should have no next item", !iter.hasNext() );
        assertTrue( "Iterator should have previous item", iter.hasPrevious() );
        assertEquals( "Iteration next index", 1, iter.nextIndex() );
        assertEquals( "Iteration previous index", 0, iter.previousIndex() );

        iterValue = iter.previous();
        assertEquals( "Iteration value is correct", testValue, iterValue );
        
        assertTrue( "Iterator should have next item", iter.hasNext() );
        assertTrue( "Iterator should have no previous item", !iter.hasPrevious() );
        assertEquals( "Iteration next index", 0, iter.nextIndex() );
        assertEquals( "Iteration previous index", -1, iter.previousIndex() );

        iterValue = iter.next();
        assertEquals( "Iteration value is correct", testValue, iterValue );
        
        assertTrue( "Iterator should have no next item", !iter.hasNext() );
        assertTrue( "Iterator should have previous item", iter.hasPrevious() );
        assertEquals( "Iteration next index", 1, iter.nextIndex() );
        assertEquals( "Iteration previous index", 0, iter.previousIndex() );

    	try {
    	    iter.next();
    	} catch (Exception e) {
    	  assertTrue("NoSuchElementException must be thrown", 
    		 e.getClass().equals((new NoSuchElementException()).getClass()));
    	}
        iter.previous();
        try {
            iter.previous();
        } catch (Exception e) {
          assertTrue("NoSuchElementException must be thrown", 
             e.getClass().equals((new NoSuchElementException()).getClass()));
        }
    }
}