def test_has_node():
g = Graph()
assert g.has_node('a') is False
g.add_node('a')
assert g.has_node('a') is True
g.add_edge('b', 'c')
assert g.has_node('b') is True
g.del_edge('b', 'c')
assert g.has_node('c') is True
def test_weighted_edges():
g = Graph()
g.add_edge('a', 'b')
g.add_edge('a', 'd')
g.add_edge('a', 'g')
g.add_edge('b', 'e')
g.add_edge('e', 'g')
g.add_edge('b', 'f')
g.add_edge('f', 'd')
g.add_edge('f', 'c')
g.add_edge('c', 'h')
assert g.adjacent('a', 'b') is True
assert g.adjacent('a', 'c') is False
g.del_edge('a', 'b')
assert g.neighbors('a') == ['d', 'g']
def test_del_edge():
g = Graph()
e1 = Edge('a', 'b')
e2 = Edge('b', 'c')
e3 = Edge('a', 'c')
edges = [e1, e2, e3]
g.add_edge('a', 'b')
g.add_edge('b', 'c')
g.add_edge('a', 'c')
for edge in edges:
assert edge in g._edges
g.del_edge('b', 'c')
assert len(g._edges) == 2
assert e2 not in g._edges
assert e1 in g._edges and e3 in g._edges
try:
g.del_edge(1, 2)
except IndexError:
assert True
else:
assert False
g.del_edge('b', 'a')
assert len(g._edges) == 1