Mock os.remove in Python with unittest.mock

Question

How do I mock os.remove with unittest.mock?

My attempt (using pytest)

def test_patch_remove():
    with patch("os.remove"):
        remove('foo')

gives the error

    remove('foo') E           FileNotFoundError: [Errno 2] No such file or directory: 'foo'

indicating that remove has not been mocked.

Answer 1

You have two possibilities: either you mock the module os and use remove from the module (test_remove1), or you do from os import remove, and mock the copy in your own module (test_remove2):

test_remove.py

import os
from os import remove
from mock import patch

def test_remove1():
    with patch('os.remove'):
        os.remove('foo')

def test_remove2():
    with patch('test_remove.remove'):
        remove('foo')

In a real test the import will happen in another module, so the second case has to be adapted to patch that module.