def test_depth_first_1():
graph = Graph()
node_1 = graph.add_node('')
actual = graph.depth_first(node_1)
expected = [node_1]
assert actual == expected
def test_depth_first_2():
graph = Graph()
node_1 = graph.add_node('')
node_2 = graph.add_node('')
node_3 = graph.add_node('')
node_4 = graph.add_node('')
graph.add_edge(node_1 , node_2 , 0)
graph.add_edge(node_1 , node_3 , 0)
graph.add_edge(node_2 , node_4 , 0)
actual = graph.depth_first(node_1)
expected = [node_1,node_2,node_4,node_3]
assert actual == expected
