def test_kruskal_raises():
g = Graph(range(10))
for v in g.vertices:
g.link(0, v, 5)
for v1 in g.vertices:
for v2 in g.vertices:
if v1 != v2 and not g.has_edge(v1, v2):
g.link(v1, v2, 10)
with pytest.raises(ValueError):
kruskal(g)
def test_hamiltonian_cycle():
g = Graph(
range(11),
zip(range(10), range(1, 10)),
)
for v in range(10):
g.link(v, 10, 2)
hc = hamiltonian_cycle(g, 0)
assert hc == list(range(11))
def test_str(g):
g = Graph()
assert str(g) == 'Graph(set(), set())'
g.insert(0)
g.insert(1)
assert str(g) == 'Graph({0, 1}, set())'
g.link(0, 1, 5)
assert str(g) == 'Graph({0, 1}, {(0, 1, 5)})'
def test_prim():
g = Graph(range(10))
for v in g.vertices:
if v != 0:
g.link(0, v, 5)
for v1 in g.vertices:
for v2 in g.vertices:
if v1 != v2 and not g.has_edge(v1, v2):
g.link(v1, v2, 10)
tree = prim(g)
assert tree.vertices == set(range(10))
assert tree.edges == {(0, i, 5) for i in range(1, 10)}
def test_fringe():
g = Graph(range(10))
g.link(0, 1)
g.link(0, 2)
g.link(0, 3)
g.link(0, 4)
g.link(1, 5)
g.link(1, 6)
g.link(1, 7)
g.link(1, 8)
g.link(2, 9)
assert fringe(g, [0]) == set(range(1, 5))
assert fringe(g, [1]) == {0} | set(range(5, 9))
assert fringe(g, [2]) == {0, 9}
assert fringe(g, [0, 1]) == set(range(2, 9))
assert fringe(g, [0, 1, 2]) == g.vertices - {0, 1, 2}
