added test for is_container

Author: tclose

pydra/utils/tests/test_typing.py

@@ -11,7 +11,7 @@
 from fileformats.generic import File
 from pydra.engine.lazy import LazyOutField
 from pydra.compose import workflow
-from pydra.utils.typing import TypeParser, MultiInputObj
+from pydra.utils.typing import TypeParser, MultiInputObj, is_container
 from fileformats.application import Json, Yaml, Xml
 from .utils import (
     GenericFuncTask,
@@ -866,6 +866,34 @@ def test_none_is_subclass2a():
     assert not TypeParser.is_subclass(None, int | float)
 
 
+@pytest.mark.parametrize(
+    ("type_",),
+    [
+        (str,),
+        (ty.List[int],),
+        (ty.Tuple[int, ...],),
+        (ty.Dict[str, int],),
+        (ty.Union[ty.List[int], ty.Tuple[int, ...]],),
+        (ty.Union[ty.List[int], ty.Dict[str, int]],),
+        (ty.Union[ty.List[int], ty.Tuple[int, ...], ty.Dict[str, int]],),
+    ],
+)
+def test_is_container(type_):
+    assert is_container(type_)
+
+
+@pytest.mark.parametrize(
+    ("type_",),
+    [
+        (int,),
+        (bool,),
+        (ty.Union[bool, str],),
+    ],
+)
+def test_is_not_container(type_):
+    assert not is_container(type_)
+
+
 @pytest.mark.skipif(
     sys.version_info < (3, 9), reason="Cannot subscript tuple in < Py3.9"
 )

pydra/utils/typing.py

@@ -1073,6 +1073,8 @@ def is_optional(type_: type) -> bool:
 def is_container(type_: type) -> bool:
     """Check if the type is a container, i.e. a list, tuple, or MultiOutputObj"""
     origin = ty.get_origin(type_)
+    if origin is ty.Union:
+        return all(is_container(a) for a in ty.get_args(type_))
     tp = origin if origin else type_
     return inspect.isclass(tp) and issubclass(tp, ty.Container)