I see, I missed the strange tuple format of this.. So you could do something like:

    [api_category['name'] for api_category in available_categories if api_category['name'] in [mock_category[0] for mock_category in mock_app['categories']]]

Of course, this might be easier to read if you split it into a couple of lines/variables.

What is the reason for using tuples instead of a dictionary or something more suitable?