test: add extra MockProtoRequest test cases to test_setup_request_id

Author: hebaalazzeh

packages/google-api-core/tests/unit/gapic/test_request.py

@@ -65,6 +65,8 @@ def __contains__(self, key):
         # MockProtoRequest cases
         (MockProtoRequest(), True, "uuid"),
         (MockProtoRequest(request_id="already_set"), True, "already_set"),
+        (MockProtoRequest(request_id=""), False, "uuid"),
+        (MockProtoRequest(request_id="already_set"), False, "already_set"),
         # ValueError case
         (MockValueErrorRequest(), True, "uuid"),
         # Dict cases
@@ -82,6 +84,8 @@ def __contains__(self, key):
         "non_proto3_optional_already_set",
         "proto3_optional_not_in_request_proto",
         "proto3_optional_already_in_request_proto",
+        "non_proto3_optional_empty_proto",
+        "non_proto3_optional_already_set_proto",
         "value_error_fallback",
         "dict_proto3_optional_not_in_request",
         "dict_proto3_optional_already_in_request",