bpo-43224: Add more tests for typevar substitution #31844
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serhiy-storchaka
approved these changes
Mar 17, 2022
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I think that it would be better to add these tests in |
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(I'll close this PR because I'd forgotten it also makes some changes to typing.py. I'll make a new PR that's purely tests-only.) |
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Here are some more tests for the updated type variable substitution logic in #31800 (along with a fix for converting e.g.
*tuple[int]into justint).There are existing tests for some of this in e.g.
TypeVarTests.test_var_substitution, but I think we can keep those tests as something more like integration tests (checking whether substitution is correct on actual aliases), regarding the tests in this PR as something closer to unit tests (testing onlytyping._determine_typevar_substitution).One thing worth explaining: I've moved the place we call
_check_genericso that we're doing all the checking for incorrect arity in one place (in_determine_typevar_substitution). This also makes testing easier - we can test for both correct and incorrect substitutions inTypeVarSubstitutionTests.These aren't yet complete. In particular:
Annotated, which @JelleZijlstra thinks there could be some issues with.TypeVarand aTypeVarTuple- e.g. substituting*tuple[int, ...]intoT, *Tsand*Ts, T(since I've yet to confirm with @pradeep90 what should even happen in these cases)Even so, I'll put this out there now so that @serhiy-storchaka has a reference of what we need to test for #31828.
https://bugs.python.org/issue43224