reverseiteratortest.java

来自「BOOK:Beginning Algorithms Code Example」· Java 代码 · 共 62 行

package com.wrox.algorithms.iteration;

import junit.framework.TestCase;

/**
 * Test cases for {@link ReverseIterator}.
 *
 */
public class ReverseIteratorTest extends TestCase {
    private static final Object[] ARRAY = new Object[] {"A", "B", "C"};

    public void testForwardsIterationBecomesBackwards() {
        ReverseIterator iterator = new ReverseIterator(new ArrayIterator(ARRAY));

        iterator.first();
        assertFalse(iterator.isDone());
        assertSame(ARRAY[2], iterator.current());

        iterator.next();
        assertFalse(iterator.isDone());
        assertSame(ARRAY[1], iterator.current());

        iterator.next();
        assertFalse(iterator.isDone());
        assertSame(ARRAY[0], iterator.current());

        iterator.next();
        assertTrue(iterator.isDone());
        try {
            iterator.current();
            fail();
        } catch (IteratorOutOfBoundsException e) {
            // expected
        }
    }

    public void testBackwardsIterationBecomesForwards() {
        ReverseIterator iterator = new ReverseIterator(new ArrayIterator(ARRAY));

        iterator.last();
        assertFalse(iterator.isDone());
        assertSame(ARRAY[0], iterator.current());

        iterator.previous();
        assertFalse(iterator.isDone());
        assertSame(ARRAY[1], iterator.current());

        iterator.previous();
        assertFalse(iterator.isDone());
        assertSame(ARRAY[2], iterator.current());

        iterator.previous();
        assertTrue(iterator.isDone());
        try {
            iterator.current();
            fail();
        } catch (IteratorOutOfBoundsException e) {
            // expected
        }
    }
}