python中的json函数,断言在python中用json字符串调用的模拟函数

迷南。 2022-10-04 13:00 17阅读 0赞

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Writing some unit tests in python and using MagicMock to mock out a method that accepts a JSON string as input. In my unit test, I want to assert that it is called with given arguments, however I run into issues with the assert statement, since the ordering of objects within the dict doesn't matter, besides in the assert statement for the string. Simplified example of what I am trying to achieve below.

mock\_funct = MagicMock()

\# mocked function called elsewhere

expected = \{"a":"a", "b":"b"\}

mock\_funct.assert\_called\_once\_with(json.dumps(expected))

The above may pass or may fail due to the arbitrary ordering of the keys within the dict when it is dumped to json, ie both '\{"a":"a", "b":"b"\}' and '\{"b":"b", "a":"a"\}' are valid dumps but one would fail and one would pass, however I would like to write the test so that either would pass.

解决方案

Unfortunately, you'll need to do your own checking here. You can get the calls from the mock via it's call\_args\_list attribute (or, simply call\_args in this case since you have already asserted that it is called only once). I'll assume you're using unittest in my example code -- but it should be easy enough to adapt for any testing framework ...

mock\_funct.assert\_called\_once\_with(mock.ANY)

call = mock\_funct.call\_args

call\_args, call\_kwargs = call \# calls are 2-tuples of (positional\_args, keyword\_args)

self.assertEqual(json.loads(call\_args\[0\]), expected)

I've still used assert\_called\_once\_with to make sure that the function was only called once with a single positional argument, but then I open up the call to look at that argument to check that it is correct.

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