Issue 35047: Better error messages in unittest.mock

Messages (8) msg328292 - (view) Author: Petter S (Petter S) * Date: 2018-10-23 08:35

When developing unit tests with `unittest.mock`, it is common to see error messages like this:

    AssertionError: Expected 'info' to not have been called. Called 3 times.

It would be really helpful if those 3 calls were listed in the assertion error.

I am happy to add this if people agree it is a good thing.

msg328344 - (view) Author: Emmanuel Arias (eamanu) * Date: 2018-10-23 20:53

It seems to be a good idea.

If you attach a sample, it would be great.

msg328378 - (view) Author: Petter S (Petter S) * Date: 2018-10-24 16:41

Sure, consider the following code:

from unittest import mock

m = mock.Mock()
m(1, 3)
m("Test", data=[42])


When I call

m.assert_not_called()

I get the following error message:

AssertionError: Expected 'mock' to not have been called. Called 2 times.

This is what I would like to improve. On the other hand, if I call

m.assert_has_calls(mock.call(3))

I get the following error:

AssertionError: Calls not found.
Expected: ['', (3,), {}]
Actual: [call(1, 3), call('Test', data=[42])]

This is great and may serve as a template for what I want to introduce.

msg328379 - (view) Author: Petter S (Petter S) * Date: 2018-10-24 16:43

(The example above should have been "m.assert_has_calls([mock.call(3)])" but it does not affect my point.)

msg328386 - (view) Author: Emmanuel Arias (eamanu) * Date: 2018-10-24 19:16

I think that is a good change. 

Maybe you can apply the change on 3.6, 3.7 and 3.8

msg328743 - (view) Author: STINNER Victor (vstinner) * Date: 2018-10-28 20:37

New changeset 47d94241a383e2b8a2c40e81d12d40d5947fb170 by Victor Stinner (Petter Strandmark) in branch 'master':
bpo-35047, unittest.mock: Better error messages on assert_called_xxx failures (GH-10090)
https://github.com/python/cpython/commit/47d94241a383e2b8a2c40e81d12d40d5947fb170

msg328745 - (view) Author: STINNER Victor (vstinner) * Date: 2018-10-28 20:42

Thanks Petter Strandmark!

msg344636 - (view) Author: STINNER Victor (vstinner) * Date: 2019-06-04 19:35

New changeset 001d63cefaa9d84d6d59aa9db8bac66040c8f0ee by Victor Stinner (Petter Strandmark) in branch 'master':
bpo-35047: Update whatsnew/3.8 for better mock error message (GH-13746)
https://github.com/python/cpython/commit/001d63cefaa9d84d6d59aa9db8bac66040c8f0ee

History Date User Action Args 2019-06-04 19:35:08vstinnersetmessages: + msg344636 2019-06-02 18:54:43Petter Ssetpull_requests: + pull_request13628 2018-10-28 20:42:15vstinnersetstatus: open -> closed
resolution: fixed
messages: + msg328745

stage: patch review -> resolved

2018-10-28 20:37:14vstinnersetnosy: + vstinner
messages: + msg328743
2018-10-27 14:46:57serhiy.storchakasetnosy: + michael.foord
2018-10-25 08:03:31Petter Ssetkeywords: + patch
stage: patch review
pull_requests: + pull_request9420 2018-10-24 19:16:58eamanusetmessages: + msg328386 2018-10-24 16:43:47Petter Ssetmessages: + msg328379 2018-10-24 16:41:40Petter Ssetmessages: + msg328378 2018-10-23 20:53:06eamanusetnosy: + eamanu
messages: + msg328344
2018-10-23 19:16:37serhiy.storchakasettitle: Better error messages un unittest.mock -> Better error messages in unittest.mock 2018-10-23 11:45:28xtreaksetnosy: + xtreak
2018-10-23 08:35:36Petter Screate