@Test public void checkKeyUpEvent() { tested = false; Button b = new Button(); b.addKeyUpHandler( new KeyUpHandler() { public void onKeyUp(KeyUpEvent event) { if (event.getNativeKeyCode() == KeyCodes.KEY_ENTER) tested = !tested; } }); // Test keyDown(b, KeyCodes.KEY_ESCAPE); // Assert Assert.assertFalse("onKeyUp event should not be triggered", tested); // Test 2 keyUp(b, KeyCodes.KEY_ENTER); // Assert 2 Assert.assertTrue("onKeyUp event was not triggered", tested); }