Turns out stuff was totally broken in these cases because we're either
closing the underlying mem chan too early or not handling the
"allow_overruns" mode's cancellation correctly..
These will verify new changes to the runtime/messaging core which allows
us to adopt an "ignore cancel if requested by us" style handling of
`ContextCancelled` more like how `trio` does with
`trio.Nursery.cancel_scope.cancel()`. We now expect
a `ContextCancelled.canceller: tuple` which is set to the actor uid of
the actor which requested the cancellation which eventually resulted in
the remote error-msg.
Also adds some experimental tweaks to the "backpressure" test which it
turns out is very problematic in coordination with context cancellation
since blocking on the feed mem chan to some task will block the ipc msg
loop and thus handling of cancellation.. More to come to both the test
and core to address this hopefully since right now this test is failing.
With the new fancy `_pytest.pathlib.import_path()` we can do real
parametrization of the example-script-module code and thus configure
whether the child, parent, or both silently break the IPC connection.
Parametrize the test for all the above mentioned cases as well as the
case where the IPC never breaks but we still simulate the user hammering
ctl-c / SIGINT to terminate the actor tree. Adjust expected errors based
on each case and heavily document each of these.
Turns out this test was being silently ignored due to incorrect usage of
sync opening of our `.open_nursery()` block (with a `with` not `async
with`) and thus was an noop XD
Instead this fixes the test to call a `tractor` discovery built-in
without starting the runtime (which is now done implicitly when a user
opens a nursery) which should result in the prior expected outcome,
a `RuntimeError`.
Tyler Goodlet