Fixed cancellation propagation in inner task groups with spawn (nedba…

…t#85)
agronholm · Nov 25, 2019 · ccfc86a · ccfc86a
1 parent 2dba52d
commit ccfc86a
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Showing 3 changed files with 25 additions and 8 deletions.
diff --git a/anyio/_backends/_asyncio.py b/anyio/_backends/_asyncio.py
@@ -364,10 +364,11 @@ def _filter_cancellation_errors(exceptions: Sequence[BaseException]) -> List[Bas
         for exc in exceptions:
             if isinstance(exc, ExceptionGroup):
                 exc.exceptions = TaskGroup._filter_cancellation_errors(exc.exceptions)
-                if len(exc.exceptions) > 1:
-                    filtered_exceptions.append(exc)
-                else:
-                    filtered_exceptions.append(exc.exceptions[0])
+                if exc.exceptions:
+                    if len(exc.exceptions) > 1:
+                        filtered_exceptions.append(exc)
+                    else:
+                        filtered_exceptions.append(exc.exceptions[0])
             elif not isinstance(exc, CancelledError):
                 filtered_exceptions.append(exc)
 

diff --git a/anyio/_backends/_curio.py b/anyio/_backends/_curio.py
@@ -303,10 +303,11 @@ def _filter_cancellation_errors(exceptions: Sequence[BaseException]) -> List[Bas
         for exc in exceptions:
             if isinstance(exc, ExceptionGroup):
                 exc.exceptions = TaskGroup._filter_cancellation_errors(exc.exceptions)
-                if len(exc.exceptions) > 1:
-                    filtered_exceptions.append(exc)
-                else:
-                    filtered_exceptions.append(exc.exceptions[0])
+                if exc.exceptions:
+                    if len(exc.exceptions) > 1:
+                        filtered_exceptions.append(exc)
+                    else:
+                        filtered_exceptions.append(exc.exceptions[0])
             elif not isinstance(exc, CancelledError):
                 filtered_exceptions.append(exc)
 

diff --git a/tests/test_taskgroups.py b/tests/test_taskgroups.py
@@ -507,3 +507,18 @@ async def fn():
     assert len(exc.value.exceptions) == 2
     assert str(exc.value.exceptions[0]) == 'parent task failed'
     assert str(exc.value.exceptions[1]) == 'child task failed'
+
+
+@pytest.mark.anyio
+async def test_cancel_propagation_with_inner_spawn():
+    async def g():
+        async with anyio.create_task_group() as g:
+            await g.spawn(anyio.sleep, 10)
+            await anyio.sleep(5)
+
+        assert False
+
+    async with anyio.create_task_group() as group:
+        await group.spawn(g)
+        await anyio.sleep(0.1)
+        await group.cancel_scope.cancel()