Python: Mocking a context manager

Question

I don\'t understand why I can\'t mock NamedTemporaryFile.name in this example:

from mock import Mock, patch
import unittest
import tempfile

def myfunc():
           


        

Answer 1

Here is an alternative with pytest and mocker fixture, which is a common practice as well:

def test_myfunc(mocker):
    mock_tempfile = mocker.MagicMock(name='tempfile')
    mocker.patch(__name__ + '.tempfile', new=mock_tempfile)
    mytmpname = 'abcde'
    mock_tempfile.NamedTemporaryFile.return_value.__enter__.return_value.name = mytmpname
    assert myfunc() == mytmpname