def test_remove_dart(self):
a = Vertex("a")
b = Vertex("b")
a.add_dart(b, 1)
# Remove the dart
a.remove_dart(b)
self.assertFalse(a.is_neighbor(b))
def test_is_neighbor(self):
a = Vertex("a")
b = Vertex("b")
a.add_dart(b, 1)
self.assertTrue(a.is_neighbor(b))
self.assertFalse(b.is_neighbor(a))
