Improve test coverage for the math module

[skirpichev]

Sometimes input checks are missing (e.g. L989 of math_1 or L1023 of math_1a), sometimes exceptional cases are not tested (e.g. in fsum), some code is just inaccessible (like L3519 in the perm_comb_small() helper). See attached coverage report (for ./python -m test test_math).

I believe, everything should be tested (except for memory errors and similar special cases).

lcov-report.zip

Linked PRs

• gh-102837: few coverage nitpicks for the math module #102523
• gh-102837: Increase test coverage for the math module #110000
• gh-102837: more tests for the math module #111930
• [3.12] gh-102837: more tests for the math module (GH-111930) #112029
• [3.12] gh-102837: more tests for the math module (GH-111930)(GH-102523) #112030
• [3.11] gh-102837: more tests for the math module (GH-111930)(GH-102523) (GH-112030) #112041

[skirpichev]

@hauntsaninja, wait. As I said in the PR thread - there are still some uncovered lines/branches. I think it's worth to keep this issue open until it's fixed completely.

[hauntsaninja]

Ah, missed that since it was early on. Re-opened!