def test_edge_change_anchor_valuerror(db_3_vertices):
"""Test if the change_anchor method raises an exception.
When the given anchor doesn't belong the the edge.
"""
db, v1, v2, v3 = db_3_vertices
e1 = Edge(v1, v2)
with pytest.raises(ValueError):
e1.change_anchor(v3)
def test_edge_change_anchor(db_3_vertices):
"""Test if the change_anchor method changes the right attributes."""
db, v1, v2, v3 = db_3_vertices
e1 = Edge(v1, v2)
e1.change_anchor(v1)
assert e1.anchor is v1
assert e1.other is v2
assert e1.direction == "out"
e1.change_anchor(v2)
assert e1.anchor is v2
assert e1.other is v1
assert e1.direction == "in"
e2 = Edge(v2, v3, has_direction=False)
e2.change_anchor(v2)
assert e2.anchor is v2
assert e2.other is v3
assert e2.direction == "none"
e2.change_anchor(v3)
assert e2.anchor is v3
assert e2.other is v2
assert e2.direction == "none"