Add `debugging/subactor_bp_in_ctx.py` test set

It's been in the debug scripts quite a while without a wrapping test and
will be,
- only the 2nd such REPL test which uses a lower-level `@context` ep-API
- the first official and explicit use of `enable_transports=['uds']`
  a suite.

Deats,
- flip to 'uds' tpt and 'devx' level logging in the script.
- add a new 2-case suite `test_ctxep_pauses_n_maybe_ipc_breaks` which
  validates both the quit-early (via `BdbQuit`) and
  channel-dropped-need-to-ctlc cases from a single test fn.

examples/debugging/subactor_bp_in_ctx.py

@@ -33,8 +33,11 @@ async def just_bp(
 
 
 async def main():
+
     async with tractor.open_nursery(
         debug_mode=True,
+        enable_transports=['uds'],
+        loglevel='devx',
     ) as n:
         p = await n.start_actor(
             'bp_boi',

tests/devx/test_debugger.py

@@ -10,10 +10,14 @@ TODO:
     - wonder if any of it'll work on OS X?
 
 """
+from __future__ import annotations
 from functools import partial
 import itertools
 import platform
 import time
+from typing import (
+    TYPE_CHECKING,
+)
 
 import pytest
 from pexpect.exceptions import (
@@ -34,6 +38,9 @@ from .conftest import (
     assert_before,
 )
 
+if TYPE_CHECKING:
+    from ..conftest import PexpectSpawner
+
 # TODO: The next great debugger audit could be done by you!
 # - recurrent entry to breakpoint() from single actor *after* and an
 #   error in another task?
@@ -1062,6 +1069,88 @@ def test_shield_pause(
     child.expect(EOF)
 
 
+@pytest.mark.parametrize(
+    'quit_early', [False, True]
+)
+def test_ctxep_pauses_n_maybe_ipc_breaks(
+    spawn: PexpectSpawner,
+    quit_early: bool,
+):
+    '''
+    Audit generator embedded `.pause()`es from within a `@context`
+    endpoint with a chan close at the end, requiring that ctl-c is
+    mashed and zombie reaper kills sub with no hangs.
+
+    '''
+    child = spawn('subactor_bp_in_ctx')
+    child.expect(PROMPT)
+
+    # 3 iters for the `gen()` pause-points
+    for i in range(3):
+        assert_before(
+            child,
+            [
+                _pause_msg,
+                "('bp_boi'",  # actor name
+                "<Task 'just_bp'",  # task name
+            ]
+        )
+        if (
+            i == 1
+            and
+            quit_early
+        ):
+            child.sendline('q')
+            child.expect(PROMPT)
+            assert_before(
+                child,
+                ["tractor._exceptions.RemoteActorError: remote task raised a 'BdbQuit'",
+                 "bdb.BdbQuit",
+                 "('bp_boi'",
+                ]
+            )
+            child.sendline('c')
+            child.expect(EOF)
+            assert_before(
+                child,
+                ["tractor._exceptions.RemoteActorError: remote task raised a 'BdbQuit'",
+                 "bdb.BdbQuit",
+                 "('bp_boi'",
+                ]
+            )
+            break  # end-of-test
+
+        child.sendline('c')
+        try:
+            child.expect(PROMPT)
+        except TIMEOUT:
+            # no prompt since we hang due to IPC chan purposely
+            # closed so verify we see error reporting as well as
+            # a failed crash-REPL request msg and can CTL-c our way
+            # out.
+            assert_before(
+                child,
+                ['peer IPC channel closed abruptly?',
+                 'another task closed this fd',
+                 'Debug lock request was CANCELLED?',
+                 "TransportClosed: 'MsgpackUDSStream' was already closed locally ?",]
+
+                # XXX races on whether these show/hit?
+                 # 'Failed to REPl via `_pause()` You called `tractor.pause()` from an already cancelled scope!',
+                 # 'AssertionError',
+            )
+            # OSc(ancel) the hanging tree
+            do_ctlc(
+                child=child,
+                expect_prompt=False,
+            )
+            child.expect(EOF)
+            assert_before(
+                child,
+                ['KeyboardInterrupt'],
+            )
+
+
 # TODO: better error for "non-ideal" usage from the root actor.
 # -[ ] if called from an async scope emit a message that suggests
 #    using `await tractor.pause()` instead since it's less overhead