def test_from_london_to_paris(self, mockk):
calculator = FlightCalculator('london', ['paris'])
flights = list(calculator.process())
self.assertEqual(1, len(flights))
self.assertEqual([self.flight1], flights)
def test_with_several_destination_cities(self, mockk):
calculator = FlightCalculator('london', ['paris', 'berlin'])
flights = list(calculator.process())
self.assertEqual(2, len(flights))
self.assertEqual([self.flight1, self.flight2], flights)