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2017-02-20

Testing uWSGI applications can be tricky because you can't actually install and import uWSGI.

It's not very well documented, but

there is no uwsgi module. It does only exist when you run the python engine from uWSGI.

Many a developer has been frustrated by this during testing running into:

import uwsgi

>> Traceback (most recent call last):
>>   File "", line 1, in 
>> ImportError: No module named uwsgi

And although much of an application can be factored out into independent testable modules you will always have a small section that remains untested unless you engage in various levels of mocking.

1. Ignore the error

The easiest way to overcome the ImportError is just to ignore it.

try:
    import uwsgi
except ImportError:
    uwsgi = None

I've never been happy with doing this. Ignoring errors in this manner is a code smell!

2. Mocking the uwsgi module at the system level

I much prefer creating a mock uwsgi module before importing any applications under test.

The gist below shows how easy it really is:

import mock
import sys

# Create a mock `uwsgi` module so that
# import uwsgi does not throw an ImportError

uwsgi = mock.MagicMock()
sys.modules.setdefault('uwsgi', uwsgi)

uwsgidecorators = mock.MagicMock()
uwsgidecorators.postfork = lambda x: x
sys.modules.setdefault('uwsgidecorators', uwsgidecorators)

3. A project for another day

I would love to be able to do

pip install mock_uwsgi

Then import it at the top of my test files

import mock_uwsgi as uwsgi