def test_cyclic_detection(self):
g = Graph()
g.add_vertex(1)
g.add_vertex(2)
g.add_vertex(3)
g.add_vertex(4)
assert g.cycle_detect() is False
# Let's add a straight line
g.add_edge(1, 2)
g.add_edge(2, 3)
assert g.cycle_detect() is False
# move from 3 to 1
g.add_edge(3, 1)
assert g.cycle_detect() is True
g.remove_edge(3, 1)
# Looping 4 to 4
g.add_edge(4, 4)
assert g.cycle_detect() is True
# Removed 4 to 4
g.remove_edge(4, 4)
assert g.cycle_detect() is False
def test_remove(self):
g = Graph()
g.add_vertex(1)
g.add_vertex(2)
g.add_vertex(3)
g.add_edge(1, 2)
g.add_edge(1, 3)
# Should be removed
g.remove_edge(1, 2)
assert 2 not in g.vertices[1]
assert 3 in g.vertices[1]
assert 1 not in g.vertices[2]
assert 3 not in g.vertices[2]
assert 1 not in g.vertices[3]
assert 2 not in g.vertices[3]
# Let's reset that and add more things that link to 3
g.add_edge(1, 2)
g.add_edge(2, 3)
assert 3 in g.vertices[1]
assert 3 in g.vertices[2]
# And remove 3
g.remove_vertex(3)
# It should stop existing, even in previous adjacincies
assert 3 not in g.vertices[1]
assert 3 not in g.vertices[2]
assert 3 not in g.vertices
# Delete something that doesn't exist,
with self.assertRaises(ValueError):
g.remove_vertex(6)
# Let's make 1 not exist
g.remove_vertex(1)
with self.assertRaises(ValueError):
g.add_edge(2, 1)
assert 1 not in g.vertices
# Adding edges
with self.assertRaises(ValueError):
g.add_edge(2, 1)
with self.assertRaises(ValueError):
g.add_edge(1, 2)
# Removing edges that can't exist, src and dest
with self.assertRaises(ValueError):
g.remove_edge(5, 6)
with self.assertRaises(ValueError):
g.remove_edge(1, 6)