Meta-issue tracking efforts towards param scope support in pytest

[blakeNaccarato]

pytest-param-scope emulates functionality that approximates what a fixture scope at the parametrized test level might achieve. In fact, native support for such a scope may come to pytest, and this issue tracks the related efforts. The following two issues directly track the interest for this feature:

• New scope designed for parametrized tests functions pytest-dev/pytest#3432
• Suggestion: add new 'parametrization' fixture scope pytest-dev/pytest#1552

However, implementation requires pytest's test collection node structure to understand functions at definition time, prior to parametrization. Also, pytest-dev/pytest#1552 (comment) and pytest-dev/pytest#1552 (comment) detail the implementation problem of how such a scope is not so simply defined, due to the fact that parametrize can be used on functions as well as fixtures, operating at various scopes. See further discussion in #1. And in pytest's backwards compatibility policy, it is explicitly stated that this feature effort constitutes a true breakage. We can see some of the broader upstream efforts related to the above feature requests:

• https://github.com/pytest-dev/pytest/projects/1 includes a FunctionDefinition node, currently inactive
  • Introduce FunctionDefinition node, use it in generate_tests pytest-dev/pytest#2522
  • See also the related API reference on FunctionDefinition
• https://github.com/pytest-dev/pytest/projects/3 seeks to clean up the node tree and pave the way forward
  • introduce FunctionDefinition with a scope to the official collection tree pytest-dev/pytest#3926

Contributors are welcome to contribute here at pytest-param-scope to improve the emulation of param scope functionality until the massive overhaul in pytest properly supports the scope. I would also like to point potentially interested contributors towards helping the upstream effort for supporting param scope in pytest. However, most of the direct blockers touch a lot of the core parts of pytest, so the work is being carried out primarily by core pytest contributors. At the time of writing, then, the best way to help out pytest upstream is to follow their contribution guide, and work on issues designated as good first issues or those marked as help wanted.

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Meta-meta-question: This developer-focused meta-issue has a lot of detail. Some of these details may be relevant to the user-focused readme documentation. If so, which details might be worth including there?

[okken]

This is a great write-up. thanks.