def test_starting_stop_equals_destination_stop():
# No need to take a bus if start and destination are the same.
routes = [[1, 2, 3, 4], [3, 4]]
assert buses_to_destination(routes, 1, 1) == 0
assert buses_to_destination(routes, 2, 2) == 0
assert buses_to_destination(routes, 3, 3) == 0
assert buses_to_destination(routes, 4, 4) == 0
def test_same_bus_route_to_destination():
routes = [[1, 2], [2, 3], [3, 4], [4, 5]]
assert buses_to_destination(routes, 1, 2) == 1
assert buses_to_destination(routes, 2, 3) == 1
assert buses_to_destination(routes, 3, 4) == 1
assert buses_to_destination(routes, 4, 5) == 1
def test_website_example():
assert buses_to_destination([[1, 2, 7], [3, 6, 7]], 1, 6) == 2
def test_only_one_bus_route_available():
routes = [[1, 2, 3, 4]]
assert buses_to_destination(routes, 1, 2) == 1
assert buses_to_destination(routes, 2, 3) == 1
assert buses_to_destination(routes, 3, 4) == 1
def test_no_route_to_destination():
routes = [[1, 2], [2, 3], [4, 5]]
assert buses_to_destination(routes, 1, 4) == -1
assert buses_to_destination(routes, 2, 4) == -1
assert buses_to_destination(routes, 3, 4) == -1
def test_two_buses_required_to_destination():
routes = [[1, 2], [2, 3], [3, 4], [4, 5]]
assert buses_to_destination(routes, 1, 3) == 2
assert buses_to_destination(routes, 2, 4) == 2
assert buses_to_destination(routes, 3, 5) == 2