ScreenMap map = new ScreenMap(xmin, ymin, width, height);
// check points outside the screen
assertFalse(map.checkAndSet(-10, -10));
assertFalse(map.checkAndSet(-10, -10));
assertFalse(map.checkAndSet(-10, 10));
assertFalse(map.checkAndSet(-10, 10));
assertFalse(map.checkAndSet(20, 10));
assertFalse(map.checkAndSet(20, 10));
assertFalse(map.checkAndSet(20, -10));
assertFalse(map.checkAndSet(20, -10));