Fixed cancel scopes becoming their own parent on asyncio and curio

Fixes nedbat#24. Closes nedbat#25.
agronholm · Oct 27, 2018 · cb979b6 · cb979b6
1 parent bb276ae
commit cb979b6
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Showing 3 changed files with 10 additions and 2 deletions.
diff --git a/anyio/_backends/asyncio.py b/anyio/_backends/asyncio.py
@@ -193,10 +193,10 @@ async def sleep(delay: float) -> None:
 @async_generator
 async def open_cancel_scope():
     task = current_task()
+    parent_scope = get_cancel_scope(task)
     scope = CancelScope()
     scope.add_task(task)
     set_cancel_scope(task, scope)
-    parent_scope = get_cancel_scope(task)
     if parent_scope is not None:
         parent_scope.children.add(scope)
 

diff --git a/anyio/_backends/curio.py b/anyio/_backends/curio.py
@@ -97,10 +97,10 @@ async def sleep(seconds: int):
 @async_generator
 async def open_cancel_scope():
     task = await curio.current_task()
+    parent_scope = get_cancel_scope(task)
     scope = CancelScope()
     scope.add_task(task)
     set_cancel_scope(task, scope)
-    parent_scope = get_cancel_scope(task)
     if parent_scope is not None:
         parent_scope.children.add(scope)
 

diff --git a/tests/test_taskgroups.py b/tests/test_taskgroups.py
@@ -199,6 +199,14 @@ async def test_escaping_cancelled_exception():
         await sleep(0)
 
 
+@pytest.mark.anyio
+async def test_cancel_scope_cleared():
+    async with move_on_after(0.1):
+        await sleep(1)
+
+    await sleep(0)
+
+
 @pytest.mark.anyio
 async def test_fail_after():
     with pytest.raises(TimeoutError):