edit_gemfile

# File railties/lib/rails/generators/rails/db/system/change/change_generator.rb, line 41
          def edit_gemfile
            name, version = database.gem
            gsub_file("Gemfile", all_database_gems_regex, name)
            gsub_file("Gemfile", gem_entry_regex_for(name), gem_entry_for(name, *version))
          end