monitor.leave();
    thread1.assertPriorCallReturns(waitFor());
  }

  public final void testWaitFor_withoutEnter() throws Exception {
    TestGuard guard = new TestGuard(true);
    thread1.callAndAssertThrows(IllegalMonitorStateException.class, waitFor(), guard);
  }

  public void testNulls() {
    monitor.enter(); // Inhibit IllegalMonitorStateException
    new NullPointerTester()