fix: type-check factor set definition ids (#16)

tests/test_factor_contracts.py

@@ -810,6 +810,56 @@ def test_external_snapshot_definition_and_view_references_cannot_be_substituted(
     )
 
 
+@pytest.mark.parametrize(
+    "invalid_definition_id",
+    [
+        {"unexpected": "object"},
+        ["array"],
+        42,
+        True,
+        None,
+    ],
+)
+def test_factor_set_ref_definition_ids_reject_non_string_types(
+    invalid_definition_id: Any,
+) -> None:
+    factor_set = _factor_set()
+    definition = _golden_definition()
+    value = factor_set.to_dict()
+    value["definition_ids"] = [definition.definition_id, invalid_definition_id]
+    _reidentify(value, "factor_set_id", "rhfactorsetv1:sha256:")
+    snapshot, foundation = _snapshot_and_foundation()
+
+    with pytest.raises(FactorContractError) as error:
+        FactorSetRef.from_json(
+            canonical_json_bytes(value),
+            definitions=(definition,),
+            dataset_snapshot=snapshot,
+            foundation=foundation,
+        )
+
+    _assert_error(error, ContractErrorCode.TYPE_ERROR, "$.definition_ids[1]")
+
+
+def test_factor_set_ref_definition_ids_still_reject_duplicate_strings() -> None:
+    factor_set = _factor_set()
+    definition = _golden_definition()
+    value = factor_set.to_dict()
+    value["definition_ids"] = [definition.definition_id, definition.definition_id]
+    _reidentify(value, "factor_set_id", "rhfactorsetv1:sha256:")
+    snapshot, foundation = _snapshot_and_foundation()
+
+    with pytest.raises(FactorContractError) as error:
+        FactorSetRef.from_json(
+            canonical_json_bytes(value),
+            definitions=(definition,),
+            dataset_snapshot=snapshot,
+            foundation=foundation,
+        )
+
+    _assert_error(error, ContractErrorCode.INVALID_VALUE, "$.definition_ids")
+
+
 def test_factor_set_parent_requires_exact_identity_and_correlation() -> None:
     parent = _factor_set()
     child_arguments = _factor_set_arguments()