Patch not mocking a module

Question

I\'m trying to mock subprocess.Popen. When I run the following code however, the mock is completely ignored and I\'m not sure why

Test Code:

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Answer 1

You're not patching in the right place. You patch where Popen is defined:

with patch('subprocess.Popen', mock_popen):

You need to patch where Popen is imported, i.e. in the "Module Code" where you have written this line:

from subprocess import Popen, PIPE

I.e., it should look something like:

with patch('myapp.mymodule.Popen', mock_popen):

For a quick guide, read the section in the docs: Where to patch.