I need to test faylilis in the presence of Vorning. For this, pytest has a -W error flag, with which the vornings throw an exception, but stop writing to stderr . How to do both at the same time?

 def foo(): warnings.warn('Some warning') def test_1(): try: foo() except Exception: processErrors()

Ps The decision to catch hands and print them yourself, unfortunately, does not fit

  • pytest writes to stderr the reason why the test fell. In this case, it will be varning. Or something else is needed? - suit
  • C -W error does not write. Instead, the Vorning throws an exception. If there is something like `` `try: foo (), warn () except Exception: processException ()` `, then the Vorning will be treated as if a normal exception has occurred and the flow will go further, and the outsider will be unaware of that that the Vorning was, since nothing is written in the stderr. To cover except Warning all tras does not suit me. I believe that there is still something appropriate in api warning / paytest - NikBond
  • from here docs.pytest.org/en/latest/warnings.html is the second example. There is a Vorning, the test falls, the observer sees that the test has fallen precisely because of the presence of the Vorning UserWarning: api v1, should use functions from v2 - suit
  • The test fell because the Vorning threw an exception. If this piece of code is wrapped in try: ... except Expection: ... it will not fall and will not output - NikBond
  • Why should you wrap them in a try? In the question, on the contrary, they wrote that they did not want to catch them with their hands - suit

2 answers 2

The essence of the -W error flag is that if pytest encounters a worning, it throws a UserWarning exception, i.e. all the code that goes in the test after vorning will not be executed, the test will fall.

Constructs except Exception: not recommended by PEP8. Here is a vivid example of yours. The logic of your test will be broken, as pytets will throw a UserWarning exception, your except will UserWarning it and the execution will go to processErrors() . And, perhaps, some unnecessary actions will be performed. And if you run without the -W error flag, then the test will go the other way, without processErrors() .

Those. The logic of the test will depend on what auxiliary parameters it run. As for me, this is ideologically wrong.

I recommend rewriting the try:... except:... constructions try:... except:... with an explicit indication of what exceptions you expect.

    except Exception: says that processErrors() expects a UserWarning exception: means either these are processErrors() problems for UserWarning to process (print a log and throw it again) or if processErrors() does not accept UserWarning from you, then except Exception: this is a bug in test_1() that needs to be fixed (so that processError() called only for exceptions that it expects, for example, to replace with except ValueError ).