def test_business_trip():
graph = Graph()
v1 = graph.add_node('Pandora')
v2 = graph.add_node('Arendelle')
v3 = graph.add_node('Metroville')
v4 = graph.add_node('Monstropolis')
v5 = graph.add_node('Narnia')
v6 = graph.add_node('Naboo')
graph.add_edge(v1, v2, 150)
graph.add_edge(v1, v3, 82)
graph.add_edge(v2, v3, 99)
graph.add_edge(v2, v4, 42)
graph.add_edge(v3, v4, 105)
graph.add_edge(v3, v5, 37)
graph.add_edge(v3, v6, 26)
graph.add_edge(v4, v6, 73)
graph.add_edge(v5, v6, 250)
cities = [v1, v2, v3]
assert graph.business_trip(cities) == (True, '$249')
