Feature or enhancement

While working on#110160 I've noticed that it is rather hard to reproduce random test failures. So, I want to propose a new feature / fix for that.

First of all, there's existing prior work of@vstinner who added--randseed flag.
Right now it is used together with-r to randomize test order and seeding random.

I propose to:

• Split--randseed into two options: test order randomization andrandom.seed usage
• Let's keep-r as-is
• Let's add--no-use-randseed flag to disable settingrandom.seed, let's always seed random by default
• Always print information about current random seed to be able to reuse it in the next runs

Example:

» ./python.exe -m test test_regrtestUsing random seed 659064820:00:00 load avg: 1.55 Run 1 test sequentially0:00:00 load avg: 1.55 [1/1] test_regrtest== Tests result: SUCCESS ==1 test OK.Total duration: 12.7 secTotal tests: run=102 skipped=2Total test files: run=1/1Result: SUCCESS

Basically, this is howhttps://github.com/pytest-dev/pytest-randomly works.

I have a PR ready.

Linked PRs

• gh-110171:libregrtest always setsrandom.seed unless--no-use-randseed is provided #110172