1 files changed, 34 insertions, 0 deletions
diff --git a/tests/extmod/asyncio_cancel_fair.py b/tests/extmod/asyncio_cancel_fair.py
new file mode 100644
index 0000000000..a1e35f82ba
--- /dev/null
+++ b/tests/extmod/asyncio_cancel_fair.py
@@ -0,0 +1,34 @@
+# Test fairness of cancelling a task
+# That tasks which continuously cancel each other don't take over the scheduler
+
+try:
+    import asyncio
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+
+async def task(id, other):
+    for i in range(3):
+        try:
+            print("start", id)
+            await asyncio.sleep(0)
+            print("done", id)
+        except asyncio.CancelledError as er:
+            print("cancelled", id)
+        if other is not None:
+            print(id, "cancels", other)
+            tasks[other].cancel()
+
+
+async def main():
+    global tasks
+    tasks = [
+        asyncio.create_task(task(0, 1)),
+        asyncio.create_task(task(1, 0)),
+        asyncio.create_task(task(2, None)),
+    ]
+    await tasks[2]
+
+
+asyncio.run(main())