Mock never called

Question

I tried to implement a mock in my unit tests but it is never called, even though it should.

tests.py

from mock import patch

class MyTest(TestCase):
    def test_add(self):
        name = 'Test'

        with patch('my_module.my_file.my_function') as add_method:
            m = MyModel(name=name)
            m.save()

        add_method.assert_called_with(name=name)

models.py

from my_module.my_file import my_function

class MyModel(Model):
    name = CharField(max_length=12)

    def save(self, *args, **kwargs):
        my_function(self.name)

        super(MyModel, self).save(*args, **kwargs)

my_file.py

def my_function(name):
    # Processing...

When I run the unit test, it just tells me the mock has not been called, though it should be, I know the script works fine. Do you have any idea/advice for me?

Answer 1

When models is imported, it runs from my_module.my_file import my_function, which is not mocked yet. When you run your test case, the my_function name in the models module is already bound to the real function: patching my_files has no effect.

What you need is to patch models.my_function:

with patch('models.my_function') as add_method:
    m = MyModel(name=name)
    m.save()

An alternative would be to patch my_file.my_function at models import time.

See where to patch documentation.