fix: handle RuntimeError correctly in run_sync (#425)

Author: hugokerstens

jupyter_core/utils/__init__.py

@@ -151,18 +151,17 @@ def wrapped(*args: Any, **kwargs: Any) -> Any:
         name = threading.current_thread().name
         inner = coro(*args, **kwargs)
         try:
-            # If a loop is currently running in this thread,
-            # use a task runner.
             asyncio.get_running_loop()
-            if name not in _runner_map:
-                _runner_map[name] = _TaskRunner()
-            return _runner_map[name].run(inner)
         except RuntimeError:
-            pass
-
-        # Run the loop for this thread.
-        loop = ensure_event_loop()
-        return loop.run_until_complete(inner)
+            # No loop running, run the loop for this thread.
+            loop = ensure_event_loop()
+            return loop.run_until_complete(inner)
+
+        # Loop is currently running in this thread,
+        # use a task runner.
+        if name not in _runner_map:
+            _runner_map[name] = _TaskRunner()
+        return _runner_map[name].run(inner)
 
     wrapped.__doc__ = coro.__doc__
     return wrapped

tests/test_utils.py

@@ -56,6 +56,24 @@ async def foo():
 
     asyncio.run(foo())
 
+    error_msg = "__foo__"
+
+    async def error():
+        raise RuntimeError(error_msg)
+
+    error_sync = run_sync(error)
+
+    def test_error_sync():
+        with pytest.raises(RuntimeError, match=error_msg):
+            error_sync()
+
+    test_error_sync()
+
+    async def with_running_loop():
+        test_error_sync()
+
+    asyncio.run(with_running_loop())
+
 
 def test_ensure_async():
     async def main():