Such that the suite verifies the wip `maybe_raise_from_masking_exc()`
will raise from a `trio.Cancelled.__context__` since I can't think of
any reason a `Cancelled` should ever be raised in-place of
a non-`Cancelled` XD
Not sure what should be raised instead (or maybe just a `log.warning()`
emitted?) but this starts a draft for refinement at the least. Use the
new `@pytest.mark.parametrize` explicit tuple-of-params form with an
`pytest.param + `.mark.xfail()` for the default behaviour case.
Since i wasted 2 days just to find an example of this inside an `@acm`,
figured I better reproduce for the purposes of maybe implementing
a warning sys (inside our wip proto `open_taskman()`) when a nursery
detects a single `Cancelled` in an eg where the `.__context__` is set to
some non-cancel error (which likely means a cancel-causing source
exception was suppressed by accident).
Left in a buncha commented code using `maybe_open_nursery()` which
i thought might be part of the issue but didn't end up being required;
will likely remove on a follow up refinement.
- `trio_typing` is nearly obsolete since `trio >= 0.23`
- `exceptiongroup` is built-in to python 3.11
- `async_generator` primitives have lived in `contextlib` for quite
a while!
Tyler Goodlet