thread1.callAndAssertBlocks(enterIf(), guard);
    thread2.callAndAssertReturns(leave());
    thread1.assertPriorCallReturns(true, enterIf());
  }

  public final void testTryEnterIf_initiallyTrue() throws Exception {
    TestGuard guard = new TestGuard(true);
    thread1.callAndAssertReturns(true, tryEnterIf(), guard);
    thread2.callAndAssertBlocks(enter());
  }