abstractfifoqueuetestcase.java

BOOK:Beginning Algorithms Code Examples

package com.wrox.algorithms.queues;

import junit.framework.TestCase;

/**
 * Abstract base class for testing FIFO {@link Queue}s.
 *
 */
public abstract class AbstractFifoQueueTestCase extends TestCase {
    private static final String VALUE_A = "A";
    private static final String VALUE_B = "B";
    private static final String VALUE_C = "C";

    private Queue _queue;

    protected void setUp() throws Exception {
        super.setUp();

        _queue = createFifoQueue();
    }

    protected abstract Queue createFifoQueue();

    public void testAccessAnEmptyQueue() {
        assertEquals(0, _queue.size());
        assertTrue(_queue.isEmpty());

        try {
            _queue.dequeue();
            fail();
        } catch (EmptyQueueException e) {
            // expected
        }
    }

    public void testEnqueueDequeue() {
        _queue.enqueue(VALUE_B);
        _queue.enqueue(VALUE_A);
        _queue.enqueue(VALUE_C);

        assertEquals(3, _queue.size());
        assertFalse(_queue.isEmpty());

        assertSame(VALUE_B, _queue.dequeue());
        assertEquals(2, _queue.size());
        assertFalse(_queue.isEmpty());

        assertSame(VALUE_A, _queue.dequeue());
        assertEquals(1, _queue.size());
        assertFalse(_queue.isEmpty());

        assertSame(VALUE_C, _queue.dequeue());
        assertEquals(0, _queue.size());
        assertTrue(_queue.isEmpty());

        try {
            _queue.dequeue();
            fail();
        } catch (EmptyQueueException e) {
            // expected
        }
    }

    public void testClear() {
        _queue.enqueue(VALUE_A);
        _queue.enqueue(VALUE_B);
        _queue.enqueue(VALUE_C);

        assertFalse(_queue.isEmpty());

        _queue.clear();

        assertEquals(0, _queue.size());
        assertTrue(_queue.isEmpty());

        try {
            _queue.dequeue();
            fail();
        } catch (EmptyQueueException e) {
            // expected
        }
    }
}