Add parent vs. child cancels first cases

examples/advanced_faults/ipc_failure_during_stream.py

@@ -46,8 +46,7 @@ async def close_stream_and_error(
 async def recv_and_spawn_net_killers(
 
     ctx: Context,
-    break_ipc: bool = False,
-    **kwargs,
+    break_ipc_after: bool | int = False,
 
 ) -> None:
     '''
@@ -63,8 +62,8 @@ async def recv_and_spawn_net_killers(
             print(f'child echoing {i}')
             await stream.send(i)
             if (
-                break_ipc
-                and i > 500
+                break_ipc_after
+                and i > break_ipc_after
             ):
                 '#################################\n'
                 'Simulating child-side IPC BREAK!\n'
@@ -76,8 +75,12 @@ async def recv_and_spawn_net_killers(
 async def main(
     debug_mode: bool = False,
     start_method: str = 'trio',
-    break_parent_ipc: bool = False,
-    break_child_ipc: bool = False,
+
+    # by default we break the parent IPC first (if configured to break
+    # at all), but this can be changed so the child does first (even if
+    # both are set to break).
+    break_parent_ipc_after: int | bool = False,
+    break_child_ipc_after: int | bool = False,
 
 ) -> None:
 
@@ -99,15 +102,15 @@ async def main(
 
         async with portal.open_context(
             recv_and_spawn_net_killers,
-            break_ipc=break_child_ipc,
+            break_ipc_after=break_child_ipc_after,
 
         ) as (ctx, sent):
             async with ctx.open_stream() as stream:
                 for i in range(1000):
 
                     if (
-                        break_parent_ipc
-                        and i > 100
+                        break_parent_ipc_after
+                        and i > break_parent_ipc_after
                     ):
                         print(
                             '#################################\n'

tests/test_advanced_faults.py

@@ -22,30 +22,56 @@ from conftest import (
 @pytest.mark.parametrize(
     'ipc_break',
     [
-        {},
-        {'break_parent_ipc': True},
-        {'break_child_ipc': True},
+        # no breaks
         {
-            'break_child_ipc': True,
-            'break_parent_ipc': True,
+            'break_parent_ipc_after': False,
+            'break_child_ipc_after': False,
         },
+
+        # only parent breaks
+        {
+            'break_parent_ipc_after': 500,
+            'break_child_ipc_after': False,
+        },
+
+        # only child breaks
+        {
+            'break_parent_ipc_after': False,
+            'break_child_ipc_after': 500,
+        },
+
+        # both: break parent first
+        {
+            'break_parent_ipc_after': 500,
+            'break_child_ipc_after': 800,
+        },
+        # both: break child first
+        {
+            'break_parent_ipc_after': 800,
+            'break_child_ipc_after': 500,
+        },
+
     ],
     ids=[
         'no_break',
         'break_parent',
         'break_child',
-        'break_both',
+        'break_both_parent_first',
+        'break_both_child_first',
     ],
 )
-def test_child_breaks_ipc_channel_during_stream(
+def test_ipc_channel_break_during_stream(
     debug_mode: bool,
     spawn_backend: str,
     ipc_break: dict | None,
 ):
     '''
-    Ensure we can (purposely) break IPC during streaming and it's still
-    possible for the (simulated) user to kill the actor tree using
-    SIGINT.
+    Ensure we can have an IPC channel break its connection during
+    streaming and it's still possible for the (simulated) user to kill
+    the actor tree using SIGINT.
+
+    We also verify the type of connection error expected in the parent
+    depending on which side if the IPC breaks first.
 
     '''
     if spawn_backend != 'trio':
@@ -66,16 +92,49 @@ def test_child_breaks_ipc_channel_during_stream(
     # when ONLY the child breaks we expect the parent to get a closed
     # resource error on the next `MsgStream.receive()` and then fail out
     # and cancel the child from there.
-    if 'break_child_ipc' in ipc_break:
+    if (
+
+        # only child breaks
+        (
+            ipc_break['break_child_ipc_after']
+            and ipc_break['break_parent_ipc_after'] is False
+        )
+
+        # both break but, parent breaks first
+        or (
+            ipc_break['break_child_ipc_after'] is not False
+            and (
+                ipc_break['break_parent_ipc_after']
+                > ipc_break['break_child_ipc_after']
+            )
+        )
+
+    ):
         expect_final_exc = trio.ClosedResourceError
 
-    # when the parent IPC side dies (even if the child's does as well)
-    # we expect the channel to be sent a stop msg from the child at some
-    # point which will signal the parent that the stream has been
-    # terminated.
-    # NOTE: when the parent breaks "after" the child you get the above
-    # case as well, but it's not worth testing right?
-    if 'break_parent_ipc' in ipc_break:
+    # when the parent IPC side dies (even if the child's does as well
+    # but the child fails BEFORE the parent) we expect the channel to be
+    # sent a stop msg from the child at some point which will signal the
+    # parent that the stream has been terminated.
+    # NOTE: when the parent breaks "after" the child you get this same
+    # case as well, the child breaks the IPC channel with a stop msg
+    # before any closure takes place.
+    elif (
+        # only parent breaks
+        (
+            ipc_break['break_parent_ipc_after']
+            and ipc_break['break_child_ipc_after'] is False
+        )
+
+        # both break but, child breaks first
+        or (
+            ipc_break['break_parent_ipc_after'] is not False
+            and (
+                ipc_break['break_child_ipc_after']
+                > ipc_break['break_parent_ipc_after']
+            )
+        )
+    ):
         expect_final_exc = trio.EndOfChannel
 
     with pytest.raises(expect_final_exc):