Add type checking test

Author: dandavison

tests/nexus/test_type_checking.py

@@ -0,0 +1,33 @@
+import nexusrpc
+
+import temporalio.nexus
+from temporalio import workflow
+
+
+def _():
+    @nexusrpc.handler.service_handler
+    class MyService:
+        @nexusrpc.handler.sync_operation
+        async def my_sync_operation(
+            self, ctx: nexusrpc.handler.StartOperationContext, input: int
+        ) -> str:
+            raise NotImplementedError
+
+        @temporalio.nexus.workflow_run_operation
+        async def my_workflow_run_operation(
+            self, ctx: temporalio.nexus.WorkflowRunOperationContext, input: int
+        ) -> temporalio.nexus.WorkflowHandle[str]:
+            raise NotImplementedError
+
+    @workflow.defn(sandboxed=False)
+    class MyWorkflow:
+        @workflow.run
+        async def invoke_nexus_op_and_assert_error(self) -> None:
+            self.nexus_client = workflow.create_nexus_client(
+                service=MyService,
+                endpoint="fake-endpoint",
+            )
+            await self.nexus_client.execute_operation(MyService.my_sync_operation, 1)
+            await self.nexus_client.execute_operation(
+                MyService.my_workflow_run_operation, 1
+            )