def test_maximum_flow_not_directed_or_multi():
exp = None
G = nx.Graph()
G.add_edge('a', 'b', capacity = 2)
G.add_edge('b', 'c', capacity = 5)
with pytest.raises(TypeError) as excinfo:
(obs_path, obs) = pa.find_maximum_flow(G, 'a', 'c')
assert 'Graph must be DiGraph type' in str(excinfo)
def test_maximum_flow_simple():
exp = 3
G = nx.DiGraph()
G.add_edge('a', 'b', capacity=3)
G.add_edge('b', 'c', capacity=4)
G.add_edge('c', 'd', capacity=3)
G.add_edge('b', 'd', capacity=10)
(obs_path, obs) = pa.find_maximum_flow(G, 'a', 'd')
assert obs == exp
def test_maximum_flow_several_paths():
exp = 3
G = nx.DiGraph()
G.add_edge('a', 'd', capacity=1)
G.add_edge('a', 'b', capacity=1)
G.add_edge('a', 'c', capacity=1)
G.add_edge('b', 'd', capacity=2)
G.add_edge('c', 'd', capacity=5)
(obs_path, obs) = pa.find_maximum_flow(G, 'a', 'd')
assert obs == exp
def test_maximum_flow_multigraph_order_flipped():
'''NetworkX retains only the most recently added edge if multiple edges
exit and a MultiGraph is converted into a DiGraph'''
exp = 2
G = nx.DiGraph()
G.add_edge('a', 'b', capacity=1)
G.add_edge('a', 'b', capacity=2)
G.add_edge('b', 'c', capacity=5)
(obs_path, obs) = pa.find_maximum_flow(G, 'a', 'c')
assert obs == exp
def test_maximum_flow_directed_only():
exp = 5
G = nx.DiGraph()
G.add_edge('a', 'b', capacity=4)
G.add_edge('a', 'c', capacity=4)
G.add_edge('b', 'd', capacity=2)
G.add_edge('b', 'e', capacity=1)
G.add_edge('c', 'd', capacity=3)
G.add_edge('d', 'e', capacity=4)
(obs_path, obs) = pa.find_maximum_flow(G, 'a', 'e')
assert obs == exp