Test fails as expected due to not wrapping non-async def op result

Author: dandavison

temporalio/worker/_nexus.py

@@ -308,10 +308,27 @@ async def run() -> temporalio.bridge.proto.nexus.NexusTaskCompletion:
                         )
                     )
                 else:
-                    raise TypeError(
+                    # TODO(dan): what should the error response be when the user has failed to wrap their return type?
+                    # TODO(dan): unify this failure completion with the path above
+                    err = TypeError(
                         "Nexus operation must return either nexusrpc.StartOperationResultSync "
                         "or nexusrpc.StartOperationResultAsync"
                     )
+                    handler_err = _exception_to_handler_error(err)
+                    return temporalio.bridge.proto.nexus.NexusTaskCompletion(
+                        task_token=task_token,
+                        error=temporalio.api.nexus.v1.HandlerError(
+                            error_type=handler_err.type.value,
+                            failure=await self._exception_to_failure_proto(
+                                handler_err.__cause__
+                            ),
+                            retry_behavior=(
+                                temporalio.api.enums.v1.NexusHandlerErrorRetryBehavior.NEXUS_HANDLER_ERROR_RETRY_BEHAVIOR_RETRYABLE
+                                if handler_err.retryable
+                                else temporalio.api.enums.v1.NexusHandlerErrorRetryBehavior.NEXUS_HANDLER_ERROR_RETRY_BEHAVIOR_NON_RETRYABLE
+                            ),
+                        ),
+                    )
 
                 return temporalio.bridge.proto.nexus.NexusTaskCompletion(
                     task_token=task_token,

tests/worker/test_nexus_handler.py

@@ -118,6 +118,7 @@ class MyService:
         Input, Output
     ]
     sync_operation_without_type_annotations: nexusrpc.interface.Operation[Input, Output]
+    sync_operation_with_non_async_def: nexusrpc.interface.Operation[Input, Output]
     non_retryable_application_error: nexusrpc.interface.Operation[Input, Output]
     retryable_application_error: nexusrpc.interface.Operation[Input, Output]
     check_operation_timeout_header: nexusrpc.interface.Operation[Input, Output]
@@ -224,6 +225,12 @@ async def async_operation(
             options=options,
         )
 
+    @nexusrpc.handler.sync_operation
+    def sync_operation_with_non_async_def(
+        self, input: Input, options: nexusrpc.handler.StartOperationOptions
+    ) -> Output:
+        return Output(value=f"from start method: {input.value}")
+
     @nexusrpc.handler.sync_operation
     async def sync_operation_without_type_annotations(self, input, options):
         return Output(
@@ -376,6 +383,15 @@ class SyncHandlerHappyPath(_TestCase):
     #     "Nexus-Link header not echoed correctly."
 
 
+class SyncHandlerHappyPathNonAsyncDef(_TestCase):
+    operation = "sync_operation_with_non_async_def"
+    input = Input("hello")
+    expected_response = SuccessfulResponse(
+        status_code=200,
+        body_json={"value": "from start method: hello"},
+    )
+
+
 class SyncHandlerHappyPathWithoutTypeAnnotations(_TestCase):
     operation = "sync_operation_without_type_annotations"
     input = Input("hello")
@@ -502,6 +518,7 @@ class OperationError(_FailureTestCase):
     "test_case",
     [
         SyncHandlerHappyPath,
+        SyncHandlerHappyPathNonAsyncDef,
         SyncHandlerHappyPathWithoutTypeAnnotations,
         AsyncHandlerHappyPath,
         AsyncHandlerHappyPathWithoutTypeAnnotations,