public TestAbandonedObjectPool(String testName) 
{
    
        super(testName);
}

 public  void setUp() throws Exception 
{
        super.setUp();
        config = new AbandonedConfig();
        // -- Uncomment the following line to enable logging -- 
        // config.setLogAbandoned(true);
        config.setRemoveAbandoned(true);
        config.setRemoveAbandonedTimeout(1);
        pool = new AbandonedObjectPool(new SimpleFactory(), config);
}

 public static Test suite() 
{
        return new TestSuite(TestAbandonedObjectPool.class);
}

 public  void tearDown() throws Exception 
{
        super.tearDown();
        pool.close();
        pool = null;
}

 public  void testConcurrentInvalidation() throws Exception 
{
        final int POOL_SIZE = 30;
        pool.setMaxActive(POOL_SIZE);
        pool.setMaxIdle(POOL_SIZE);
        pool.setWhenExhaustedAction(AbandonedObjectPool.WHEN_EXHAUSTED_FAIL);
        // Exhaust the connection pool
        Vector vec = new Vector();
        for (int i = 0; i <  POOL_SIZE; i++) {
            vec.add(pool.borrowObject());
        }
        // Abandon all borrowed objects
        for (int i = 0; i <  vec.size(); i++) {
            ((PooledTestObject)vec.elementAt(i)).setAbandoned(true);
        }
        // Try launching a bunch of borrows concurrently.  Abandoned sweep will be triggered for each.
        final int CONCURRENT_BORROWS = 5;
        Thread[] threads = new Thread[CONCURRENT_BORROWS];
        for (int i = 0; i <  CONCURRENT_BORROWS; i++) {
            threads[i] = new ConcurrentBorrower(vec);
            threads[i].start();
        }
        // Wait for all the threads to finish
        for (int i = 0; i <  CONCURRENT_BORROWS; i++) {
            threads[i].join();
        }
        // Return all objects that have not been destroyed
        for (int i = 0; i <  vec.size(); i++) {
            PooledTestObject pto = (PooledTestObject)vec.elementAt(i);
            if (pto.isActive()) {
                pool.returnObject(pto);
            }
        }
        // Now, the number of open connections should be 0
        assertTrue("numActive should have been 0, was " + pool.getNumActive(), pool.getNumActive() == 0);
}

Tests fix for Bug 28579, a bug in AbandonedObjectPool that causes numActive to go negative in GenericObjectPool