Add support for metadata attributes for enum values (#7567) (#7568)

* Add support for metadata attributes for enum values (#7567)

* Fix path lookup in flatc test

* Try a fix for Windows paths

* Convert path to string to fix Windows error

tests/flatc/flatc_schema_tests.py

@@ -0,0 +1,43 @@
+# Copyright 2022 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from flatc_test import *
+import json
+
+
+class SchemaTests:
+    def EnumValAttributes(self):
+        # Generate .bfbs schema first
+        flatc(["--schema", "--binary", "--bfbs-builtins", "enum_val_attributes.fbs"])
+        assert_file_exists("enum_val_attributes.bfbs")
+
+        # Then turn it into JSON
+        flatc(["--json", "--strict-json", str(reflection_fbs_path()), "--", "enum_val_attributes.bfbs"])
+
+        # The attributes should be present in JSON
+        schema_json = json.loads(get_file_contents("enum_val_attributes.json"))
+
+        assert schema_json["enums"][0]["name"] == "ValAttributes"
+        assert schema_json["enums"][0]["values"][0]["name"] == "Val1"
+        assert schema_json["enums"][0]["values"][0]["attributes"][0]["key"] == "display_name"
+        assert schema_json["enums"][0]["values"][0]["attributes"][0]["value"] == "Value 1"
+
+        assert schema_json["enums"][0]["values"][1]["name"] == "Val2"
+        assert schema_json["enums"][0]["values"][1]["attributes"][0]["key"] == "display_name"
+        assert schema_json["enums"][0]["values"][1]["attributes"][0]["value"] == "Value 2"
+
+        assert schema_json["enums"][0]["values"][2]["name"] == "Val3"
+        assert schema_json["enums"][0]["values"][2]["attributes"][0]["key"] == "deprecated"
+        assert schema_json["enums"][0]["values"][2]["attributes"][1]["key"] == "display_name"
+        assert schema_json["enums"][0]["values"][2]["attributes"][1]["value"] == "Value 3 (deprecated)"