As reported at:http://code.google.com/p/mock/issues/detail?id=209>>> from unittest import mock[107971 refs]>>> mock.mock_open<function mock_open at 0x10cff9d20>[107974 refs]>>> a = mock.mock_open()[109965 refs]>>> a.reset_mock()...

The best way to solve this seems to be to track a set of visited ids (mocks we've reset) and not recurse into mocks we've already done. This is similar to the patch proposed on the google code issue - but not identical as that uses a list and has it as the default argument to reset_mock.

Hi all,I've fixed the infinite recursion in `reset_mock()`. It has been solved by tracking a set of visited ids as suggested.>>> from unittest import mock>>> a = mock.mock_open()>>> a.reset_mock()>>> a<MagicMock name='open' spec='builtin_function_or_method' id='4449688192'>

The proposed patch does solve the infinite recursion bug, but a different problem appears when resetting the same mock multiple times: it only works the first time.Using the patch as it stands:>>> from unittest.mock import mock_open>>> mo = mock_open()>>> a = mo()>>> mo.call_count1>>> mo.reset_mock()>>> mo.call_count0>>> b = mo()>>> mo.call_count1>>> mo.reset_mock()>>> mo.call_count1And here from a version with an added print(visited) statement:>>> from unittest.mock import mock_open>>> mo = mock_open()>>> a = mo()>>> mo.call_count1>>> mo.reset_mock()[][139803191795152][139803191795152, 139803181189008][139803191795152, 139803181189008, 139803213598416][139803191795152, 139803181189008, 139803213598416, 139803213652048][139803191795152, 139803181189008, 139803213598416, 139803213652048]>>> mo.call_count0>>> b = mo()>>> mo.call_count1>>> mo.reset_mock()[139803191795152, 139803181189008, 139803213598416, 139803213652048, 139803213598288]>>> mo.call_count1>>> mo.reset_mock(visited=[])[][139803191795152][139803191795152, 139803181189008][139803191795152, 139803181189008, 139803213598416][139803191795152, 139803181189008, 139803213598416, 139803213652048][139803191795152, 139803181189008, 139803213598416, 139803213652048]>>> mo.call_count0As you can see, for some reason I don't quite grasp, the 'visited' parameter persists across calls to reset_mock(), meaning that the very first call does indeed reset it but subsequent calls do not.As the last two calls show, one can force a reset by explicitly providing an empty list, but this is starting to become a change in API and not just a bugfix...

Sorry Michael, I should have read your second comment more closely since you already pointed out that using a list as default argument is bad.It is, however, easily fixed by changing to this:def reset_mock(self, visited=None):    "Restore the mock object to its initial state."    if visited is None:        visited = []    if id(self) in visited:        return

I should have read more carefully, too! Thanks to both.

And here's an actual patch with the corrected code

I've been bitten by this issue with a custom psycopg2 mock.>>> cur = mock.Mock()>>> >>> cur.connection.cursor.return_value = cur>>> cur.reset_mock()RuntimeError: maximum recursion depth exceededthe patch looks ok, except the mix of tab and spaces :-)

Applying this to 3.4 and up with a test.Laurent, it would be good to sign the CLA - since your change here is minimal and Nicola has, I'm just going ahead.

New changeset4c8cb603ab42 by Robert Collins in branch '3.4':- Issue#18622: unittest.mock.mock_open().reset_mock would recurse infinitely.https://hg.python.org/cpython/rev/4c8cb603ab42

New changesetc0ec61cf5a7d by Robert Collins in branch '3.5':- Issue#18622: unittest.mock.mock_open().reset_mock would recurse infinitely.https://hg.python.org/cpython/rev/c0ec61cf5a7dNew changeseta4fe32477df6 by Robert Collins in branch 'default':- Issue#18622: unittest.mock.mock_open().reset_mock would recurse infinitely.https://hg.python.org/cpython/rev/a4fe32477df6