@Test public void testIsValid() { Diagram diagram = Diagram.newInstance() .addNode("n1", 0.0, 0.0, 100.0, 80.0) .addNode("n2", 200.0, 0.0, 300.0, 80.0); assertTrue(diagram.isValid()); diagram.addNode("n3", 0.0, 0.0, 0.0, 0.0); assertFalse(diagram.isValid()); diagram.canvas.children.remove(2); assertTrue(diagram.isValid()); diagram.addNode("n4", 0.0, 0.0, 0.0, 80.0); assertFalse(diagram.isValid()); diagram.canvas.children.remove(2); assertTrue(diagram.isValid()); diagram.addNode("n5", 400.0, 0.0, 500.0, 0.0); assertFalse(diagram.isValid()); } }