Counting calls to method inside method in Python unittest

Question

I am trying to check how many times I call the acc.add method in the Car.run method using Python unittest, but I can't figure out how to do it. This is what I tried:

Car and Accessories:

class Accessories(AccessoriesAbstract):
    def __init__(self):
        self.sum = 0
        super().__init__()

    def add(self, index, name):
        self.sum += index
        return self.sum


class Car(CarAbstract):
    def __init__(self, acc: Accessories):
        self.acc = acc
        super().__init__(acc)

    def run(self):
        self.acc.add(2, "bob")
        result = self.acc.add(5, "rob")

        if result > int(sys.maxsize) - 10:
            raise ValueError

And test:

    @patch('car_code.Car')
    def test_car_run(self, MockCar):
        car = MockCar()
        response = car.run()

        self.assertIsNotNone(response)
        car.run.acc.add.assert_called()

Answer 1

You need to mock an instance of the Accessories class instead and then pass that instance to the Car constructor. For example:

# Create an Accessories object   
acc = Accessories()
# Create a mock object that "wraps" the Accessories object
mock_acc = Mock(wraps=acc)
# Pass the mock object when you create the Car object
car = Car(mock_acc) 
car.run()
# Then you'll be able to get the call_count like this:
mock_acc.add.call_count