mocking subprocess.Popen dependant on import style

Question

When attempting to mock Popen I can only get it to succeed if the importing of subprocess matches in both unit test code and main module code.

Given following module

Answer 1

You need to patch the copy of Popen in listdir, not the one you just imported. So, instead of @mock.patch.object(subprocess, 'Popen', autospec=True), try @mock.patch.object(listdir, 'Popen', autospec=True)

See this doc for more info: http://www.voidspace.org.uk/python/mock/patch.html#where-to-patch