Allow parametrize to depend on previous parametrize

[Anton3]

Closes: #13233

[RonnyPfannschmidt]

the exposure of callspec, the hook order change as well as future considerations make this one extra hard to review

I'll need to schedule something for that

[RonnyPfannschmidt]

We should introduce a new method name for this and mark it experimental to avoid locking into callspec as exposed api too early

I'm not sure what a fitting name would be

[Anton3]

An alternative to exposing CallSpec is, as I said, to add a new Node subtype with an additional getparam method. If it was a Node, the hook from docs

    def pytest_generate_tests(metafunc: pytest.Metafunc):
        if "bar" in metafunc.fixturenames:
            # parametrize "bar" arg based on "bar_params" mark
            base_bar_marks = list(metafunc.definition.iter_markers("bar_params"))

            def gen_params(callspec: pytest.CallSpec):
                # collect all marks
                bar_marks = base_bar_marks + [
                    mark for mark in callspec.marks if mark.name == "bar_params"
                ]
                # collect all args from all marks
                return [arg for mark in bar_marks for arg in mark.args]

            metafunc.parametrize("bar", gen_params)

would be rewritten as just:

    def pytest_generate_tests(metafunc: pytest.Metafunc):
        if "bar" in metafunc.fixturenames:
            def gen_params(proto_item: pytest.ProtoItem):
                bar_marks = proto_item.iter_markers("bar_params")
                return [arg for mark in bar_marks for arg in mark.args]

            metafunc.parametrize("bar", gen_params)

[RonnyPfannschmidt]

I would like to avoid using nodes or node lookalikes

In fact thinking about potentially nesting and/or cascading I'd like to defer inventing new apis

Just ensuring the apis to experiment/ learn from this are experimental

We can't hope to initially account for something like acting in the bases of mark coming in from lazy fixtures

[Anton3]

@RonnyPfannschmidt I've figured out the ordering issue I struggled with

I can add parametrize_experimental that has everything of the normal parametrize, plus the new feature. What do you think?