[New-bugs-announce] [issue35753] Importing call from unittest.mock directly causes ValueError

David Antonini report at bugs.python.org
Wed Jan 16 15:17:24 EST 2019

New submission from David Antonini <davidantonini at hotmail.com>:

Ok so that's a pretty odd bug. I already had from unittest.mock import patch, mock_open so I simply modified that to from  instead of doing mock.call in my test. Changing this to from unittest import mock and then mock.call fixed the error.

from unittest.mock import patch, mock_open, call

    call("first print"),
    call("second print"),

I get: 

C:\Program Files (x86)\Python37-64\lib\doctest.py:932: in find
    self._find(tests, obj, name, module, source_lines, globs, {})
C:\Program Files (x86)\Python37-64\lib\doctest.py:991: in _find
    if ((inspect.isroutine(inspect.unwrap(val))
C:\Program Files (x86)\Python37-64\lib\inspect.py:515: in unwrap
    raise ValueError('wrapper loop when unwrapping {!r}'.format(f))
E   ValueError: wrapper loop when unwrapping call
collected 1 item / 1 errors

But when I don't import call directly my test runs as expected:

from unittest.mock import patch, mock_open

import unittest.mock


I have the same issue when using:

assert mocked_print.call_args_list == [call("first print"), call("second print")] <- ValueError
assert mocked_print.call_args_list == [mock.call("first print"), mock.call("second print")] <- Works as expected.

components: Tests
messages: 333786
nosy: toonarmycaptain
priority: normal
severity: normal
status: open
title: Importing call from unittest.mock directly causes ValueError
type: behavior
versions: Python 3.7

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