Prefer actual-expected to expected-actual in assertions#5129
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finswimmer merged 1 commit intoFeb 3, 2022
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danieleades
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Relates-to: #4776
As far as I know, there is no general convention about the order (actual-expected vs. expected-actual) in pytest assertions. However, I think a consistent order is desirable in order to quickly grasp what is going wrong in a failing test.
In my opinion, there is at least one strong argument for actual-expected:
SIM300offlake8-simplifyis about avoiding yoda conditions. Thus,age == 42is preferred to42 == age. Avoiding yoda conditions often results in actual-expected order.Further, most examples in pytest documentation are in actual-expected order, e.g. https://docs.pytest.org/en/6.2.x/index.html. (The same applies to unittest: https://docs.python.org/3/library/unittest.html) Probably, actual-expected is the more natural or at least more common order.
I am not aware if there is a linter that can help to keep actual-expected order because sometimes the context is required in order to decide which is actual and which is expected. At least, if most of the tests use a consistent order it will be more likely that this order is used in new tests.