def test_Parent_NoDoubleSet(self):
parent = KeyedNode("parent")
child = KeyedNode("child")
child.set_parent(parent)
imposter = KeyedNode("imposter")
self.assertRaises(MultipleParentsNotSupported,
lambda: child.set_parent(imposter))
self.assertEqual(child.get_parent(), parent)
def test_Parent_CanSet(self):
parent = KeyedNode("parent")
child = KeyedNode("child")
child.set_parent(parent)
self.assertEqual(child.get_parent(), parent)
def test_Parent_DefaultNone(self):
child = KeyedNode("child")
self.assertIsNone(child.get_parent())