Heroku and gemfile conditions

error

       You are trying to install in deployment mode after changing
       your Gemfile. Run `bundle install` elsewhere and add the
       updated Gemfile.lock to version control.
       You have deleted from the Gemfile:
       * rb-fsevent
 !
 !     Failed to install gems via Bundler.
 !
 !     Heroku push rejected, failed to compile Ruby/rails app

gemfile

group :test, :darwin do
  gem 'rb-fsevent'
end