def test_get_unvisited_neighbor__none_available():
start_v = Vertex('1')
end_v = Vertex('2')
start_v.connect(end_vertex=end_v)
end_v.visited = True
assert start_v.get_unvisited_neighbor() is None
def test_get_unvisited_neighbor__valid_result():
start_v = Vertex('1')
end_v = Vertex('2')
start_v.connect(end_vertex=end_v)
result = start_v.get_unvisited_neighbor()
assert result == end_v