Bring back unary operator

spec/controllers/omniauth_callbacks_controller_spec.rb

@@ -10,7 +10,7 @@ describe OmniauthCallbacksController, type: :controller do
     let(:additional_info) { {} }
     before do
-      @original_env_config_omniauth_auth = mock_auth_hash(provider.to_s, String.new(extern_uid), user.email, additional_info: additional_info )
+      @original_env_config_omniauth_auth = mock_auth_hash(provider.to_s, +extern_uid, user.email, additional_info: additional_info )
       stub_omniauth_provider(provider, context: request)
     end
@@ -111,7 +111,7 @@ describe OmniauthCallbacksController, type: :controller do
     context 'strategies' do
       shared_context 'sign_up' do
-        let(:user) { double(email: String.new("new@example.com")) }
+        let(:user) { double(email: +'new@example.com') }
         before do
           stub_omniauth_setting(block_auto_created_users: false)