public void testNullMonitorInGuardConstructorThrowsNPE() {
    assertThrows(NullPointerException.class, () -> new FlagGuard(null));
  }

  public void testIsFair() {
    assertTrue(new Monitor(true).isFair());
    assertFalse(new Monitor(false).isFair());
  }

  public void testOccupiedMethods() {
    Monitor monitor = new Monitor();
    verifyOccupiedMethodsInCurrentThread(monitor, false, false, 0);

  public void testNullMonitorInGuardConstructorThrowsNPE() {
    assertThrows(NullPointerException.class, () -> new FlagGuard(null));
  }

  public void testIsFair() {
    assertTrue(new Monitor(true).isFair());
    assertFalse(new Monitor(false).isFair());
  }

  public void testOccupiedMethods() {
    Monitor monitor = new Monitor();
    verifyOccupiedMethodsInCurrentThread(monitor, false, false, 0);

                  try {
                    peeker.getDone(input2Failed);
                    fail("Peeker.getDone() should fail for failed inputs");
                  } catch (ExecutionException expected) {
                  }
                  try {
                    peeker.getDone(nonInput);
                    fail("Peeker should not be able to peek into non-input ClosingFuture.");

        } catch (Exception e) {
            fail("writeThreadDump should handle invalid paths gracefully: " + e.getMessage());
        }
    }

    @Test
    public void test_writeThreadDump_withNullPath() {
        try {
            ThreadDumpUtil.writeThreadDump(null);
            // Should not throw exception but log warning
        } catch (Exception e) {

                  try {
                    peeker.getDone(input2Failed);
                    fail("Peeker.getDone() should fail for failed inputs");
                  } catch (ExecutionException expected) {
                  }
                  try {
                    peeker.getDone(nonInput);
                    fail("Peeker should not be able to peek into non-input ClosingFuture.");

                  + ".");
      return;
    }
    fail();
  }

  public void testEqualsOnReturnValues_bad() throws Exception {
    try {
      tester.forAllPublicStaticMethods(BadEqualsFactory.class).testEquals();
    } catch (AssertionError expected) {
      return;
    }
    fail();
  }

  private static class BadEqualsFactory {

    // The opposite order should fail (Policies.THROW).
    PotentialDeadlockException firstException = null;
    lockB.lock();
    PotentialDeadlockException expected =
        assertThrows(PotentialDeadlockException.class, () -> lockA.lock());
    checkMessage(expected, "LockB -> LockA", "LockA -> LockB");
    firstException = expected;
    // Second time should also fail, with a cached causal chain.

    // The opposite order should fail (Policies.THROW).
    PotentialDeadlockException firstException = null;
    lockB.lock();
    PotentialDeadlockException expected =
        assertThrows(PotentialDeadlockException.class, () -> lockA.lock());
    checkMessage(expected, "LockB -> LockA", "LockA -> LockB");
    firstException = expected;
    // Second time should also fail, with a cached causal chain.

    @Override
    public void oneArg(String s) {
      // Fail: missing NPE for s
    }
  }

  public void testFailOneArgDoesntThrowNpe() {
    shouldFail(new FailOneArgDoesntThrowNpe());
  }

  private static class FailOneArgThrowsWrongType extends PassObject {
    @Override
    public void oneArg(String s) {
      doThrow(s); // Fail: throwing non-NPE exception for null s
    }
  }

    // Test add method with null name
    @Test
    public void test_add_nullName() {
        TestScriptEngine engine = new TestScriptEngine();
        try {
            scriptEngineFactory.add(null, engine);
            fail("Should throw IllegalArgumentException for null name");
        } catch (IllegalArgumentException e) {
            assertTrue(e.getMessage().contains("Both name and scriptEngine parameters are required"));