Patching (mock) fails if custom patch value is provided with mock.patch/mock.patch.object

[debayanray]

I am running a test case under a test class as:

@ddt.ddt
class IloCommonModuleTestCase(unittest.TestCase):

    @mock.patch.object(time, 'sleep', lambda x: None)
    def test_case1(self, sleep_mock):
        pass

    @ddt.data(
          ('data1_to_test_case'),
          ('data2_to_test_case'),
          ...,
     )
    @ddt.unpack
    def test_case2(self, test_sample_data):
        pass

wherein I have other test cases which uses ddt.data and ddt.unpack as depicted. Now when I run the test cases it fails in the test_case1 and I believe this i something to do with ddt:

Traceback (most recent call last):
  File ".../local/lib/python2.7/site-packages/mock/mock.py", line 1305, in patched
    return func(*args, **keywargs)
TypeError: test_case1() takes exactly 2 arguments (1 given)

But if I remove the custom value in the patching decorator, then it works fine.

    @mock.patch.object(time, 'sleep')
    def test_case1(self, sleep_mock):
        pass

Hence, I feel there's something which is missing, like you can provide custom value to patch decorators with mock, while the class under test gets decorated by @ddt.ddt Thank you.

[txels]

My guess is that this has nothing to do with ddt, and you are just using @mock.patch.object incorrectly. When you use the 3-arg version of patch.object, it won't pass a mock as an additional argument to your function, since it doesn't create one.

See http://www.voidspace.org.uk/python/mock/patch.html#patch-object for details.

Have you tried just removing the ddt class decorator and seeing how it fails?

[debayanray]

thank you very much, @txels
yes, you were right. I was wrong in interpreting and was using the 3rd argument with patchers in a wrong manner. Thanks for pin-pointing the issue.
👍