The unittest.mock.call object could have args/kwargs attributes to easily access the arguments it was called with.

args and kwargs property can be introduced on the call object to return the args and kwargs stored in the tuple. Currently wrapping call object with tuple can get a tuple of args and kwargs but a property would be helpful. A first attempt patch on this. Feedback on the API would be helpful.

$ ./python.exe
Python 3.8.0a1+ (heads/master:8a03ff2ff4, Feb  9 2019, 10:42:29)
[Clang 7.0.2 (clang-700.1.81)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from unittest.mock import Mock
>>> m = Mock()
>>> m(1, a=1)
<Mock name='mock()' id='4325199504'>
>>> m.call_args_list[0]
call(1, a=1)
>>> tuple(m.call_args_list[0]) # wrapping it with tuple can give args and kwargs currently
((1,), {'a': 1})
>>> m.call_args_list[0].args # With patch return args
(1,)
>>> m.call_args_list[0].kwargs # With patch return kwargs
{'a': 1}

A simple patch would be as below :

➜ cpython git:(master) ✗ git diff | cat
diff --git a/Lib/unittest/mock.py b/Lib/unittest/mock.py
index ef5c55d6a1..ef1aa1dcea 100644
--- a/Lib/unittest/mock.py
+++ b/Lib/unittest/mock.py
@@ -2124,6 +2124,24 @@ class _Call(tuple):
def index(self, *args, **kwargs):
return self.__getattr__('index')(*args, **kwargs)

+ @Property
+ def args(self):
+ if len(self) == 2:
+ args, kwargs = self
+ else:
+ name, args, kwargs = self
+
+ return args
+
+ @Property
+ def kwargs(self):
+ if len(self) == 2:
+ args, kwargs = self
+ else:
+ name, args, kwargs = self
+
+ return kwargs
+
def __repr__(self):
if not self._mock_from_kall:
name = self._mock_name or 'call'

Hey @XTreak, if you're not working on this, can I submit the patch?

@kakshay, I am not working on it so feel free to pick it up. I stumbled upon this while looking into mock issues and I just posted a patch to gather API feedback. I guess it would be helpful if someone confirms it would be a good addition so that there is less rework.

Thanks

Thanks @XTreak!
I've added a PR with the following API

➜  cpython git:(fix-issue-21269) ✗ ./python.exe
Python 3.8.0a0 (heads/fix-issue-21269-dirty:2433a2ab70, Feb 10 2019, 14:24:54)
[Clang 10.0.0 (clang-1000.10.44.4)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from unittest.mock import Mock
>>> m = Mock()
>>> m(1, a=23)
<Mock name='mock()' id='4552188368'>
>>> m.call_args
call(1, a=23)
>>> m.call_args.args     #after this patch
(1,)
>>> m.call_args.kwargs   #after this patch
{'a': 23}
>>> m.call_args_list[0].args    #after this patch
(1,)
>>> m.call_args_list[0].kwargs   #after this patch
{'a': 23}

I like this patch, working with calls often feels weird and this change simplify attribute access.

@XTreak, couldn't we have made _Call inherit from namedtuple to achieve a similar result (albeit the handling of name would be weird)?

This feels safer to me with respect to backwards compatibility and also that it might be easier to backport this to mock on GitHub which works with Python 2.7. I have less knowledge on difference between tuple and namedtuple internals so I might be wrong here.

ping..😬

New changeset b0df45e by Chris Withers (Kumar Akshay) in branch 'master':
bpo-21269: Provide args and kwargs attributes on mock call objects GH11807
b0df45e

Thanks @kakshay for the patch.