Make "-" argument separator in parametrised test logs configurable

Improve readability of test running reports

pytest uses the - character to separate test parameter values in logs. There is no official API to change this string.

A hacky was is:

from _pytest.python import CallSpec2

def pytest_sessionstart(session: Session) -> None:

    def format_idlist(self: CallSpec2) -> str:
        return " | ".join(filter(None, self._idlist))

    setattr(CallSpec2, "id", property(format_idlist))

Describe the solution you'd like

It would be nice to have either a variable or callable somewhere in Session to change - to any string, like |, for example.

Start by tracing how _pytest.python.CallSpec2 builds its id from _idlist and how pytest_sessionstart can access session state. Check the existing test coverage around parametrised test reporting, then define and verify a supported variable or callable that changes the separator from "-" to a configured string such as "|".