def test_vertex_count(self) -> None:
g = Graph([(1, 2), (2, 3), (3, 4)])
assert g.vertex_count == 4, "graph should have 4 vertices"
g.add_vertex(5)
assert g.vertex_count == 5, "graph should have 5 vertices"
g.remove_vertex(5)
assert g.vertex_count == 4, "graph should have 4 vertices"
def test_remove_vertex(self) -> None:
g = Graph([(1, 2), (3, 3)])
g.add_vertex(4)
assert g.has_vertex(4), "graph should have vertex 4"
g.remove_vertex(4)
assert not g.has_vertex(
4), "graph should not have vertex 4 after removal"
assert g.has_vertex(3), "graph should have semi-isolated vertex 3"
g.remove_vertex(3)
assert not g.has_vertex(
3), "graph should not have vertex 3 after removal"
with pytest.raises(exception.VertizeeException):
g.remove_vertex(1)
