How to check with pytest if one function was called inside Django form save method? - django

Question

What i Have
Within the save method of the form are called two functions: generate_random_password and send_email, I need to know if these functions were called because generate_random_password assigns a password randomly to each new created user and send_email sends a email notification to the user with the credentials, the password generated and the user to login. It is important to know if these functions were executed correctly within save.
class UserAdminCreationForm(forms.ModelForm):
class Meta:
model = User
fields = ()
def save(self, commit: bool = True) -> U:
user = super(UserAdminCreationForm, self).save(commit=False)
data = self.cleaned_data
# Set random password for every new user
random_password = generate_random_password()
user.set_password(random_password)
# Send email confirmation with credentials to login
email = data.get("email")
html_message = render_to_string(
template_name="mails/user_creation_notification.html",
context={"email": email, "password": random_password},
)
# Strip the html tag. So people can see the pure text at least.
plain_message = strip_tags(html_message)
send_mail(
subject="Bienvenido a TodoTránsito",
message=plain_message,
recipient_list=[email],
html_message=html_message,
)
# Save into the DB the new user
if commit:
user.save()
return user
The problem
I'm using pytest to test my Django code, but I don't know how to assert if these functions were called.

Answer 1

From what you wrote in the comments, I would guess mocking both functions could make sense, as you probably don't really need the random password in your test. You could do something like:
from unittest import mock
#mock.patch('some_module.generate_random_password', return_value='swordfish')
#mock.patch('some_module.send_mail')
def test_save_user(mocked_send_mail, mocked_generate_password):
user_form = create_user_form() # whatever you do to create the form in the test
user_from.save()
mocked_generate_password.assert_called_once()
mocked_send_mail.assert_called_once()
# or mocked_send_mail.assert_called_once_with(...) if you want to check the parameters it was called with
Note that you have to make sure to mock the correct module, e.g. the one used in the tested code (see where to patch).
In this case generate_random_password is replaced with a mock that always returns the same password, and send_mail is replaced by a mock that does nothing except recording calls. Both mocks can be accessed via the arguments in the test, that are injected by the patch decorators (last decorator first, the argument names are arbitrary).
If you install pytest-mock, you get the mocker fixture, that gives you the same functionality and more. The same code would like like this:
def test_save_user(mocker):
mocked_generate_password = mocker.patch('some_module.generate_random_password', return_value='swordfish')
mocked_send_mail = mocker.patch('some_module.send_mail')
user_form = create_user_form() # whatever you do to create the form in the test
user_from.save()
mocked_generate_password.assert_called_once()
mocked_send_mail.assert_called_once()
If you now want to use the real generate_random_password, but still want to see if it was called, you can use mocker.spy instead:
def test_save_user(mocker):
mocked_generate_password = mocker.spy(some_module, 'generate_random_password')
mocked_send_mail = mocker.patch('some_module.send_mail')
user_form = create_user_form() # whatever you do to create the form in the test
user_from.save()
mocked_generate_password.assert_called_once()
mocked_send_mail.assert_called_once()
Note that you can achieve the same with unittest.mock.patch.object, but less convenient, in my opinion.