} catch (Exception e) {
        AssertionFailedError afe = new AssertionFailedError("Unexpected exception: " + e);
        afe.initCause(e);
        throw afe;
      }
    }
  }

  void checkEmpty(BlockingQueue<?> q) {
    try {
      assertTrue(q.isEmpty());
      assertEquals(0, q.size());
      assertNull(q.peek());
      assertNull(q.poll());
      assertNull(q.poll(0, MILLISECONDS));