How to test or mock "if __name__ == '__main__'" contents

Question

Say I have a module with the following:

def main():     pass  if __name__ == "__main__":     main() 

I want to write a unit test for the bottom half (I'd like to achieve 100% coverage). I discovered the runpy builtin module that performs the import/__name__-setting mechanism, but I can't figure out how to mock or otherwise check that the main() function is called.

This is what I've tried so far:

import runpy import mock  @mock.patch('foobar.main') def test_main(self, main):     runpy.run_module('foobar', run_name='__main__')     main.assert_called_once_with() 

Answer 1

I will choose another alternative which is to exclude the if __name__ == '__main__' from the coverage report , of course you can do that only if you already have a test case for your main() function in your tests.

As for why I choose to exclude rather than writing a new test case for the whole script is because if as I stated you already have a test case for your main() function the fact that you add an other test case for the script (just for having a 100 % coverage) will be just a duplicated one.

For how to exclude the if __name__ == '__main__' you can write a coverage configuration file and add in the section report:

[report]  exclude_lines =     if __name__ == .__main__.: 

More info about the coverage configuration file can be found here.

Hope this can help.

Answer 2

You can do this using the imp module rather than the import statement. The problem with the import statement is that the test for '__main__' runs as part of the import statement before you get a chance to assign to runpy.__name__.

For example, you could use imp.load_source() like so:

import imp runpy = imp.load_source('__main__', '/path/to/runpy.py') 

The first parameter is assigned to __name__ of the imported module.