Add test for propagation of optional var

src/spox/_fields.py

@@ -155,10 +155,7 @@ def fully_typed(self) -> bool:
 
 @dataclass
 class BaseInputs(BaseVarInfos):
-    def vars(self, prop_values: Optional[PropDict] = None) -> BaseVars:
-        if prop_values is None:
-            prop_values = {}
-
+    def vars(self, prop_values: PropDict) -> BaseVars:
         vars_dict: dict[str, Union[Var, Optional[Var], Sequence[Var]]] = {}
 
         for field in dataclasses.fields(self):
@@ -169,10 +166,7 @@ def vars(self, prop_values: Optional[PropDict] = None) -> BaseVars:
                 prop_value = cast(PropValue, prop_values.get(field.name, None))
                 vars_dict[field.name] = Var(field_value, prop_value)
 
-            elif (
-                field_type == VarFieldKind.OPTIONAL
-                and prop_values.get(field.name, None) is not None
-            ):
+            elif field_type == VarFieldKind.OPTIONAL:
                 prop_value = cast(PropValue, prop_values.get(field.name, None))
                 vars_dict[field.name] = Var(field_value, prop_value)
 

tests/test_value_propagation.py

@@ -122,6 +122,15 @@ def test_empty_optional_has_no_element():
     )
 
 
+@pytest.mark.parametrize("min", [None, 2])
+def test_optional_clip(min):
+    min_var = min if min is None else op.const(min)
+    assert_equal_value(
+        op.clip(op.const([1, 2, 3]), min=min_var, max=op.const(3)),
+        np.clip([1, 2, 3], a_min=min, a_max=3),
+    )
+
+
 def test_sequence_empty():
     assert_equal_value(op.sequence_empty(dtype=np.float32), [])