I have three functions that I'm trying to test the call order of.
Let's say that in module module.py I have the following
# module.py
def a(*args):
# do the first thing
def b(*args):
# do a second thing
def c(*args):
# do a third thing
def main_routine():
a_args = ('a')
b_args = ('b')
c_args = ('c')
a(*a_args)
b(*b_args)
c(*c_args)
I want to check that b is called after a, and before c. So getting a mock for each of a, b and c is easy:
# tests.py
@mock.patch('module.a')
@mock.patch('module.b')
@mock.patch('module.c')
def test_main_routine(c_mock, b_mock, a_mock):
# test all the things here
Checking that each of the individial mocks are called is easy, too. How do I check the order of the calls relative to one another?
call_args_list won't work as it's maintained separately for each mock.
I've tried using a side effect to log each of the calls:
calls = []
def register_call(*args):
calls.append(mock.call(*args))
return mock.DEFAULT
a_mock.side_effect = register_call
b_mock.side_effect = register_call
c_mock.side_effect = register_call
But this only gives me the args that the mocks were called with, but not the actual mock that the call was made against. I can add a bit more logic:
# tests.py
from functools import partial
def register_call(*args, **kwargs):
calls.append(kwargs.pop('caller', None), mock.call(*args, **kwargs))
return mock.DEFAULT
a_mock.side_effect = partial(register_call, caller='a')
b_mock.side_effect = partial(register_call, caller='b')
c_mock.side_effect = partial(register_call, caller='c')
And that seems to get the job done... Is there a better way though? It feels like there should already be something in the API that can do this that I'm missing.
Define a Mock manager and attach mocks to it via attach_mock(). Then check for the mock_calls:
@patch('module.a')
@patch('module.b')
@patch('module.c')
def test_main_routine(c, b, a):
manager = Mock()
manager.attach_mock(a, 'a')
manager.attach_mock(b, 'b')
manager.attach_mock(c, 'c')
module.main_routine()
expected_calls = [call.a('a'), call.b('b'), call.c('c')]
assert manager.mock_calls == expected_calls
Just to test that it works, change the order of function calls in the main_routine() function add see that it throws AssertionError.
See more examples at Tracking order of calls and less verbose call assertions (link is dead; substitute: https://docs.python.org/3/library/unittest.mock.html#attaching-mocks-as-attributes)
Hope that helps.