Add a helper to return all the secure types
diff --git a/test/cpp/util/test_credentials_provider.cc b/test/cpp/util/test_credentials_provider.cc
index f8380cd..6965170 100644
--- a/test/cpp/util/test_credentials_provider.cc
+++ b/test/cpp/util/test_credentials_provider.cc
@@ -70,5 +70,11 @@
   return nullptr;
 }
 
+std::vector<grpc::string> GetSecureCredentialsTypeList() {
+  std::vector<grpc::string> types;
+  types.push_back(kTlsCredentialsType);
+  return types;
+}
+
 }  // namespace testing
 }  // namespace grpc