Updated test for a safer version of Draft202012.

tests/test_validate_artifacts.py

@@ -17,11 +17,19 @@ def test_validate_json_schema(self):
         assert_that(json_schema_file_path).exists().is_file()
 
         with open(json_schema_file_path) as f:
-            json_schema = json.load(f)
+            try:
+                json_schema = json.load(f)
+            except json.JSONDecodeError as e:
+                fail(f'JSON Schema {json_schema_file_path} is not a valid JSON document: {e}')
+
             assert_that(json_schema).is_not_empty()
 
+            # Idea from https://github.com/Julian/jsonschema/issues/348#issuecomment-647418176
+            class SaferDraft202012Validator(jsonschema.Draft202012Validator):
+                META_SCHEMA = {**jsonschema.Draft202012Validator.META_SCHEMA, "additionalProperties": False}
+
             try:
-                jsonschema.Draft7Validator.check_schema(json_schema)
+                SaferDraft202012Validator.check_schema(json_schema)
             except jsonschema.exceptions.SchemaError as e:
-                fail(f'JSON Schema {json_schema_file_path} is not valid: {e}')
+                fail(f'JSON Schema {json_schema_file_path} is not a valid JSON Schema: {e}')