def __edge_view_returns_false_if_node_isnt_in_graph():
# given
g = DirectedGraph()
# when
g.add_edge(1, 3)
g.add_edge(3, 1)
# then
assert (5, 2) not in g
def test_directed_add_edge_and_opposite():
# given
g = DirectedGraph()
# when
g.add_edge(1, 3)
g.add_edge(3, 1)
# then
assert set(g.edges) == {(1, 3), (3, 1)}
def test_remove_node_removes_edges_too_directed():
# given
g = DirectedGraph()
# when
g.add_edge(1, 3)
g.add_edge(3, 1)
g.add_edge(5, 1)
g.add_edge(1, 6)
g.add_edge(1, 1)
g.remove_node(1)
assert (1, 3) not in g.edges
assert (3, 1) not in g.edges
assert (5, 1) not in g.edges
assert len(g.edges) == 0
def test_remove_missing_edge_raises_directed():
# given
g = DirectedGraph()
g.add_edge(1, 2)
g.add_edge(2, 3)
g.add_edge(3, 1)
# when
with pytest.raises(DoesNotExistError):
g.remove_edge(2, 4)
def test_remove_missing_node_raises_directed():
# given
g = DirectedGraph()
g.add_node(1)
g.add_node(2)
g.add_node(3)
# when
with pytest.raises(DoesNotExistError):
g.remove_node(4)
def test_remove_edge_directed():
# given
g = DirectedGraph()
g.add_edge(1, 2)
g.add_edge(2, 1)
g.add_edge(2, 3)
g.add_edge(3, 1)
# when
g.remove_edge(1, 2)
# then
assert (1, 2) not in g.edges
assert (2, 1) in g.edges
assert len(g.edges) == 3
assert len(g.nodes) == 3
def test_directed_predecessors():
# given
g = DirectedGraph()
# when
g.add_edge(1, 3)
g.add_edge(3, 1)
g.add_edge(5, 1)
g.add_edge(1, 6)
# then
assert set(g.predecessors(1)) == {3, 5}
assert set(g.predecessors(6)) == {1}
def test_directed_successors():
# given
g = DirectedGraph()
# when
g.add_edge(1, 3)
g.add_edge(3, 1)
g.add_edge(5, 1)
g.add_edge(1, 6)
# then
assert set(g.successors(1)) == {3, 6}
assert set(g.successors(6)) == set()
def test_directed_has_edge():
# given
g = DirectedGraph()
# when
g.add_edge(1, 3)
g.add_edge(3, 1)
g.add_edge(5, 1)
g.add_edge(1, 6)
# then
assert (1, 3) in g.edges
assert (3, 1) in g.edges
assert (5, 1) in g.edges
assert (1, 5) not in g.edges