Support various output tuple annotation (#1186)

**Pull Request Checklist**
- [x] Fixes #1167 
- [x] Tests added
- [x] Documentation/examples added; bug fix
- [x] [Good commit messages](https://cbea.ms/git-commit/) and/or PR
title

**Description of PR**
Currently, hera doesn't support un-annotated tuple output type, and
there's no guard for partially annotated type.

So updating hera like as following.
- Support un-annotated tuple output.
- Raise the error when the output tuple is partially annotated.

---------

Signed-off-by: Ukjae Jeong <[email protected]>
Signed-off-by: Ukjae Jeong <[email protected]>
Co-authored-by: Elliot Gunton <[email protected]>
Co-authored-by: Alice <[email protected]>

src/hera/workflows/script.py

@@ -555,8 +555,19 @@ def _extract_return_annotation_output(source: Callable) -> List:
     if get_workflow_annotation(return_annotation):
         output.append(annotation_args)
     elif origin_type is tuple:
-        for annotated_type in annotation_args:
-            output.append(get_args(annotated_type))
+        workflow_args = [
+            get_args(annotated_type) for annotated_type in annotation_args if get_workflow_annotation(annotated_type)
+        ]
+
+        # If all tuple elements are annotated as Parameter/Artifact
+        if len(workflow_args) == len(annotation_args):
+            output.extend(workflow_args)
+        # Only some tuple elements are annotated as Parameter/Artifact
+        elif workflow_args:
+            raise ValueError(
+                f"Function '{source.__name__}' output has partially annotated tuple return type. "
+                "Tuple elements must be all Annotated as Parameter/Artifact, or contain no Parameter/Artifact annotations for a raw tuple return type."
+            )
     elif (
         origin_type is None
         and isinstance(return_annotation, type)

tests/script_runner/parameter_with_complex_types.py

@@ -1,8 +1,13 @@
 import sys
-from typing import Optional, Union
+from typing import Optional, Tuple, Union
+
+if sys.version_info >= (3, 9):
+    from typing import Annotated
+else:
+    from typing_extensions import Annotated
 
 from hera.shared import global_config
-from hera.workflows import script
+from hera.workflows import Parameter, script
 
 global_config.experimental_features["script_annotations"] = True
 
@@ -36,3 +41,13 @@ def optional_int_parameter(my_int: Optional[int] = None) -> Optional[int]:
 @script(constructor="runner")
 def union_parameter(my_param: Union[str, int] = None) -> Union[str, int]:
     return my_param
+
+
+@script(constructor="runner")
+def fn_with_output_tuple(my_string: str) -> Tuple[str, str]:
+    return my_string, my_string
+
+
+@script(constructor="runner")
+def fn_with_output_tuple_partially_annotated(my_string: str) -> Tuple[str, Annotated[str, Parameter(name="sample")]]:
+    return my_string, my_string

tests/test_runner.py

@@ -1095,6 +1095,11 @@ def test_script_optional_parameter(
             [{"name": "my_param", "value": 123}],
             "123",
         ],
+        [
+            "tests.script_runner.parameter_with_complex_types:fn_with_output_tuple",
+            [{"name": "my_string", "value": "123"}],
+            '["123", "123"]',
+        ],
     ],
 )
 def test_script_with_complex_types(
@@ -1111,3 +1116,20 @@ def test_script_with_complex_types(
 
     # THEN
     assert serialize(output) == expected_output
+
+
+def test_script_partially_annotated_tuple_should_raise_an_error(monkeypatch: pytest.MonkeyPatch):
+    # GIVEN
+    monkeypatch.setenv("hera__script_annotations", "")
+    entrypoint = "tests.script_runner.parameter_with_complex_types:fn_with_output_tuple_partially_annotated"
+    kwargs_list = [{"name": "my_string", "value": "123"}]
+
+    # WHEN/THEN
+    with pytest.raises(
+        ValueError,
+        match=(
+            "Function 'fn_with_output_tuple_partially_annotated' output has partially annotated tuple return type. "
+            "Tuple elements must be all Annotated as Parameter/Artifact, or contain no Parameter/Artifact annotations for a raw tuple return type."
+        ),
+    ):
+        _runner(entrypoint, kwargs_list)