Fix deserialization for str unions (#1239)

**Pull Request Checklist**
- [ ] Fixes #<!--issue number goes here-->
- [X] Tests added
- [ ] Documentation/examples added
- [X] [Good commit messages](https://cbea.ms/git-commit/) and/or PR
title

**Description of PR**
PR #1168 changed the logic of `map_runner_input` and `_parse` to no
longer pass incoming values to `json.loads` if their annotated type was
a union that included str, rather than only when given a subtype of
`Optional[str]`. This makes it impossible to, for instance, pass an int
to a `Union[str, int]`.

This PR splits `origin_type_issubclass` into two functions,
`origin_type_issupertype` (which matches the previous behaviour) and
`origin_type_issubtype`, and use the latter instead to restore the
original behaviour.

Additionally, it fixes a bug where we were passing an annotation to
`issubclass` without first checking if it's a type, resulting in a
`TypeError` (partially addresses #1173).

---------

Signed-off-by: Alice Purcell <alicederyn@gmail.com>

src/hera/shared/_type_util.py

@@ -92,13 +92,26 @@ def get_unsubscripted_type(t: Any) -> Any:
     return t
 
 
-def origin_type_issubclass(cls: Any, type_: type) -> bool:
-    """Return True if cls can be considered as a subclass of type_."""
-    unwrapped_type = unwrap_annotation(cls)
+def origin_type_issubtype(annotation: Any, type_: Union[type, Tuple[type, ...]]) -> bool:
+    """Return True if annotation is a subtype of type_.
+
+    type_ may be a tuple of types, in which case return True if annotation is a subtype
+    of the union of the types in the tuple.
+    """
+    unwrapped_type = unwrap_annotation(annotation)
+    origin_type = get_unsubscripted_type(unwrapped_type)
+    if origin_type is Union or origin_type is UnionType:
+        return all(origin_type_issubtype(arg, type_) for arg in get_args(unwrapped_type))
+    return isinstance(origin_type, type) and issubclass(origin_type, type_)
+
+
+def origin_type_issupertype(annotation: Any, type_: type) -> bool:
+    """Return True if annotation is a supertype of type_."""
+    unwrapped_type = unwrap_annotation(annotation)
     origin_type = get_unsubscripted_type(unwrapped_type)
     if origin_type is Union or origin_type is UnionType:
-        return any(origin_type_issubclass(arg, type_) for arg in get_args(cls))
-    return issubclass(origin_type, type_)
+        return any(origin_type_issupertype(arg, type_) for arg in get_args(unwrapped_type))
+    return isinstance(origin_type, type) and issubclass(type_, origin_type)
 
 
 def is_subscripted(t: Any) -> bool:

src/hera/workflows/_runner/script_annotations_util.py

@@ -3,15 +3,21 @@
 import inspect
 import json
 import os
+import sys
 from pathlib import Path
 from typing import Any, Callable, Dict, List, Optional, Tuple, Type, TypeVar, Union, cast
 
+if sys.version_info >= (3, 10):
+    from types import NoneType
+else:
+    NoneType = type(None)
+
 from hera.shared._pydantic import BaseModel, get_field_annotations, get_fields
 from hera.shared._type_util import (
     get_unsubscripted_type,
     get_workflow_annotation,
     is_subscripted,
-    origin_type_issubclass,
+    origin_type_issubtype,
     unwrap_annotation,
 )
 from hera.shared.serialization import serialize
@@ -138,7 +144,7 @@ def map_runner_input(
     input_model_obj = {}
 
     def load_parameter_value(value: str, value_type: type) -> Any:
-        if origin_type_issubclass(value_type, str):
+        if origin_type_issubtype(value_type, (str, NoneType)):
             return value
 
         try:

src/hera/workflows/_runner/util.py

@@ -6,13 +6,19 @@
 import inspect
 import json
 import os
+import sys
 from pathlib import Path
 from typing import Any, Callable, Dict, List, Optional, cast
 
+if sys.version_info >= (3, 10):
+    from types import NoneType
+else:
+    NoneType = type(None)
+
 from hera.shared._pydantic import _PYDANTIC_VERSION
 from hera.shared._type_util import (
     get_workflow_annotation,
-    origin_type_issubclass,
+    origin_type_issubtype,
     unwrap_annotation,
 )
 from hera.shared.serialization import serialize
@@ -125,7 +131,7 @@ def _get_unannotated_type(key: str, f: Callable) -> Optional[type]:
 def _is_str_kwarg_of(key: str, f: Callable) -> bool:
     """Check if param `key` of function `f` has a type annotation that can be interpreted as a subclass of str."""
     if func_param_annotation := _get_function_param_annotation(key, f):
-        return origin_type_issubclass(func_param_annotation, str)
+        return origin_type_issubtype(func_param_annotation, (str, NoneType))
     return False
 
 

src/hera/workflows/script.py

@@ -47,7 +47,7 @@
     _flag_enabled,
 )
 from hera.shared._pydantic import _PYDANTIC_VERSION, root_validator, validator
-from hera.shared._type_util import get_workflow_annotation, is_subscripted, origin_type_issubclass
+from hera.shared._type_util import get_workflow_annotation, is_subscripted, origin_type_issupertype
 from hera.shared.serialization import serialize
 from hera.workflows._context import _context
 from hera.workflows._meta_mixins import CallableTemplateMixin
@@ -540,7 +540,9 @@ class will be used as inputs, rather than the class itself.
             else:
                 default = MISSING
 
-            if origin_type_issubclass(func_param.annotation, NoneType) and (default is MISSING or default is not None):
+            if origin_type_issupertype(func_param.annotation, NoneType) and (
+                default is MISSING or default is not None
+            ):
                 raise ValueError(f"Optional parameter '{func_param.name}' must have a default value of None.")
 
             parameters.append(Parameter(name=func_param.name, default=default))

tests/script_runner/parameter_inputs.py

@@ -1,5 +1,5 @@
 import json
-from typing import Any, List
+from typing import Any, List, Union
 
 try:
     from typing import Annotated
@@ -76,6 +76,11 @@ def no_type_parameter(my_anything) -> Any:
     return my_anything
 
 
+@script()
+def str_or_int_parameter(my_str_or_int: Union[int, str]) -> str:
+    return f"type given: {type(my_str_or_int).__name__}"
+
+
 @script()
 def str_parameter_expects_jsonstr_dict(my_json_str: str) -> dict:
     return json.loads(my_json_str)

tests/test_runner.py

@@ -65,6 +65,18 @@
             {},
             id="no-type-dict",
         ),
+        pytest.param(
+            "tests.script_runner.parameter_inputs:str_or_int_parameter",
+            [{"name": "my_str_or_int", "value": "hi there"}],
+            "type given: str",
+            id="str-or-int-given-str",
+        ),
+        pytest.param(
+            "tests.script_runner.parameter_inputs:str_or_int_parameter",
+            [{"name": "my_str_or_int", "value": "3"}],
+            "type given: int",
+            id="str-or-int-given-int",
+        ),
         pytest.param(
             "tests.script_runner.parameter_inputs:str_parameter_expects_jsonstr_dict",
             [{"name": "my_json_str", "value": json.dumps({"my": "dict"})}],

tests/test_unit/test_shared_type_utils.py

@@ -1,4 +1,14 @@
-from typing import List, Optional, Union
+import sys
+from typing import List, NoReturn, Optional, Union
+
+if sys.version_info >= (3, 9):
+    from typing import Annotated
+else:
+    from typing_extensions import Annotated
+if sys.version_info >= (3, 10):
+    from types import NoneType
+else:
+    NoneType = type(None)
 
 import pytest
 from annotated_types import Gt
@@ -8,16 +18,12 @@
     get_unsubscripted_type,
     get_workflow_annotation,
     is_annotated,
-    origin_type_issubclass,
+    origin_type_issubtype,
+    origin_type_issupertype,
     unwrap_annotation,
 )
 from hera.workflows import Artifact, Parameter
 
-try:
-    from typing import Annotated
-except ImportError:
-    from typing_extensions import Annotated
-
 
 @pytest.mark.parametrize("annotation, expected", [[Annotated[str, "some metadata"], True], [str, False]])
 def test_is_annotated(annotation, expected):
@@ -104,11 +110,33 @@ def test_get_unsubscripted_type(annotation, expected):
 @pytest.mark.parametrize(
     "annotation, target, expected",
     [
-        [List[str], str, False],
-        [Optional[str], str, True],
-        [str, str, True],
-        [Union[int, str], int, True],
+        pytest.param(List[str], str, False, id="list-str-not-subtype-of-str"),
+        pytest.param(NoReturn, str, False, id="special-form-does-not-raise-error"),
+        pytest.param(Optional[str], str, False, id="optional-str-not-subtype-of-str"),
+        pytest.param(str, str, True, id="str-is-subtype-of-str"),
+        pytest.param(Union[int, str], int, False, id="union-int-str-not-subtype-of-str"),
+        pytest.param(Optional[str], (str, NoneType), True, id="optional-str-is-subtype-of-optional-str"),
+        pytest.param(Annotated[Optional[str], "foo"], (str, NoneType), True, id="annotated-optional"),
+        pytest.param(str, (str, NoneType), True, id="str-is-subtype-of-optional-str"),
+        pytest.param(Union[int, str], (str, NoneType), False, id="union-int-str-not-subtype-of-optional-str"),
+    ],
+)
+def test_origin_type_issubtype(annotation, target, expected):
+    assert origin_type_issubtype(annotation, target) is expected
+
+
+@pytest.mark.parametrize(
+    "annotation, target, expected",
+    [
+        pytest.param(List[str], str, False, id="list-str-not-supertype-of-str"),
+        pytest.param(NoReturn, str, False, id="special-form-does-not-raise-error"),
+        pytest.param(Optional[str], str, True, id="optional-str-is-supertype-of-str"),
+        pytest.param(str, str, True, id="str-is-supertype-of-str"),
+        pytest.param(Union[int, str], int, True, id="union-int-str-is-supertype-of-int"),
+        pytest.param(Optional[str], NoneType, True, id="optional-str-is-supertype-of-nonetype"),
+        pytest.param(Annotated[Optional[str], "foo"], NoneType, True, id="annotated-optional"),
+        pytest.param(str, NoneType, False, id="str-not-supertype-of-nonetype"),
     ],
 )
-def test_origin_type_issubclass(annotation, target, expected):
-    assert origin_type_issubclass(annotation, target) is expected
+def test_origin_type_issupertype(annotation, target, expected):
+    assert origin_type_issupertype(annotation, target) is expected