reference_task should inherit from PythonTask

flytekit/core/interface.py

@@ -369,7 +369,9 @@ def transform_interface_to_list_interface(
     return Interface(inputs=map_inputs, outputs=map_outputs)
 
 
-def transform_function_to_interface(fn: typing.Callable, docstring: Optional[Docstring] = None) -> Interface:
+def transform_function_to_interface(
+    fn: typing.Callable, docstring: Optional[Docstring] = None, is_reference_entity: bool = False
+) -> Interface:
     """
     From the annotations on a task function that the user should have provided, and the output names they want to use
     for each output parameter, construct the TypedInterface object
@@ -382,9 +384,12 @@ def transform_function_to_interface(fn: typing.Callable, docstring: Optional[Doc
     return_annotation = type_hints.get("return", None)
 
     ctx = FlyteContextManager.current_context()
+
+    # Check if the function has a return statement at compile time locally.
+    # Skip it if the function is a reference task/workflow since it doesn't have a body.
     if (
-        ctx.execution_state
-        # Only check if the task/workflow has a return statement at compile time locally.
+        not is_reference_entity
+        and ctx.execution_state
         and ctx.execution_state.mode is None
         # inspect module does not work correctly with Python <3.10.10. https://github.com/flyteorg/flyte/issues/5608
         and sys.version_info >= (3, 10, 10)

flytekit/core/task.py

@@ -11,7 +11,7 @@
 
 from flytekit.core import launch_plan as _annotated_launchplan
 from flytekit.core import workflow as _annotated_workflow
-from flytekit.core.base_task import TaskMetadata, TaskResolverMixin
+from flytekit.core.base_task import PythonTask, TaskMetadata, TaskResolverMixin
 from flytekit.core.interface import transform_function_to_interface
 from flytekit.core.pod_template import PodTemplate
 from flytekit.core.python_function_task import PythonFunctionTask
@@ -371,7 +371,7 @@ def wrapper(fn: Callable[P, Any]) -> PythonFunctionTask[T]:
         return wrapper
 
 
-class ReferenceTask(ReferenceEntity, PythonFunctionTask):  # type: ignore
+class ReferenceTask(ReferenceEntity, PythonTask):  # type: ignore
     """
     This is a reference task, the body of the function passed in through the constructor will never be used, only the
     signature of the function will be. The signature should also match the signature of the task you're referencing,
@@ -412,7 +412,7 @@ def reference_task(
     """
 
     def wrapper(fn) -> ReferenceTask:
-        interface = transform_function_to_interface(fn)
+        interface = transform_function_to_interface(fn, is_reference_entity=True)
         return ReferenceTask(project, domain, name, version, interface.inputs, interface.outputs)
 
     return wrapper

tests/flytekit/integration/remote/test_remote.py

@@ -399,7 +399,7 @@ def test_execute_reference_task(register):
         version=VERSION,
     )
     def t1(a: int) -> nt:
-        return nt(t1_int_output=a + 2, c="world")
+        ...
 
     remote = FlyteRemote(Config.auto(config_file=CONFIG), PROJECT, DOMAIN)
     execution = remote.execute(

tests/flytekit/unit/core/test_imperative.py

@@ -327,7 +327,7 @@ def ref_t1(
         dataframe: pd.DataFrame,
         imputation_method: str = "median",
     ) -> pd.DataFrame:
-        return dataframe
+        ...
 
     @reference_task(
         project="flytesnacks",
@@ -340,7 +340,7 @@ def ref_t2(
         split_mask: int,
         num_features: int,
     ) -> pd.DataFrame:
-        return dataframe
+        ...
 
     wb = ImperativeWorkflow(name="core.feature_engineering.workflow.fe_wf")
     wb.add_workflow_input("sqlite_archive", FlyteFile[typing.TypeVar("sqlite")])

tests/flytekit/unit/core/test_references.py

@@ -81,7 +81,7 @@ def test_ref_task_more():
         version="553018f39e519bdb2597b652639c30ce16b99c79",
     )
     def ref_t1(a: typing.List[str]) -> str:
-        return "hello"
+        ...
 
     @workflow
     def wf1(in1: typing.List[str]) -> str:
@@ -106,7 +106,7 @@ def test_ref_task_more_2():
         version="553018f39e519bdb2597b652639c30ce16b99c79",
     )
     def ref_t1(a: typing.List[str]) -> str:
-        return "hello"
+        ...
 
     @reference_task(
         project="flytesnacks",
@@ -115,7 +115,7 @@ def ref_t1(a: typing.List[str]) -> str:
         version="553018f39e519bdb2597b652639c30ce16b99c79",
     )
     def ref_t2(a: typing.List[str]) -> str:
-        return "hello"
+        ...
 
     @workflow
     def wf1(in1: typing.List[str]) -> str:
@@ -435,7 +435,7 @@ def test_ref_dynamic_task():
         version="553018f39e519bdb2597b652639c30ce16b99c79",
     )
     def ref_t1(a: int) -> str:
-        return "hello"
+        ...
 
     @task
     def t2(a: str, b: str) -> str:

tests/flytekit/unit/remote/test_remote.py

@@ -15,7 +15,7 @@
 from mock import ANY, MagicMock, patch
 
 import flytekit.configuration
-from flytekit import CronSchedule, ImageSpec, LaunchPlan, WorkflowFailurePolicy, task, workflow
+from flytekit import CronSchedule, ImageSpec, LaunchPlan, WorkflowFailurePolicy, task, workflow, reference_task
 from flytekit.configuration import Config, DefaultImages, Image, ImageConfig, SerializationSettings
 from flytekit.core.base_task import PythonTask
 from flytekit.core.context_manager import FlyteContextManager
@@ -527,6 +527,22 @@ def wf(name: str = "union"):
     version_from_hash_mock.assert_called_once_with(md5_bytes, mock.ANY, mock.ANY, image_spec.image_name())
     register_workflow_mock.assert_called_once()
 
+    @reference_task(
+        project="flytesnacks",
+        domain="development",
+        name="flytesnacks.examples.basics.basics.workflow.slope",
+        version="v1",
+    )
+    def ref_basic(x: typing.List[int], y: typing.List[int]) -> float:
+        ...
+
+    @workflow
+    def wf1(name: str = "union") -> float:
+        return ref_basic(x=[1, 2, 3], y=[4, 5, 6])
+
+    flyte_remote = FlyteRemote(config=Config.auto(), default_project="p1", default_domain="d1")
+    flyte_remote.register_script(wf1)
+
 
 @mock.patch("flytekit.remote.remote.FlyteRemote.client")
 def test_local_server(mock_client):