Factor out AppBase::GemfileEntry#to_s

railties/lib/rails/generators/app_base.rb

@@ -268,6 +268,13 @@ module Rails
             version
           end
         end
+
+        def to_s
+          [ ("# #{comment}\n" if comment),
+            ("# " if commented_out), "gem \"#{name}\"", (", \"#{version}\"" if version),
+            *options.map { |key, val| ", #{key}: #{val.inspect}" }
+          ].compact.join
+        end
       end
 
       def rails_prerelease?

railties/lib/rails/generators/rails/app/templates/Gemfile.tt

@@ -2,14 +2,10 @@ source "https://rubygems.org"
 git_source(:github) { |repo| "https://github.com/#{repo}.git" }
 
 ruby <%= "\"#{RUBY_VERSION}\"" -%>
-<% gemfile_entries.each do |gem| -%>
-<% if gem.comment %>
 
-# <%= gem.comment %>
+<% gemfile_entries.each do |gemfile_entry| %>
+<%= gemfile_entry %>
 <% end -%>
-<%= gem.commented_out ? "# " : "" %>gem "<%= gem.name %>"<%= %(, "#{gem.version}") if gem.version -%>
-<% if gem.options.any? -%>, <%= gem.options.map { |k,v| "#{k}: #{v.inspect}" }.join(", ") %><% end -%>
-<% end %>
 <% unless options.minimal? -%>
 
 # Use Kredis to get higher-level data types in Redis [https://github.com/rails/kredis]

railties/lib/rails/generators/rails/plugin/templates/Gemfile.tt

@@ -17,17 +17,8 @@ end
 <% if rails_prerelease? -%>
 # Your gem is dependent on a prerelease version of Rails. Once you can lock this
 # dependency down to a specific version, move it to your gemspec.
-<% max_width = gemfile_entries.map { |g| g.name.length }.max -%>
-<% gemfile_entries.each do |gem| -%>
-<% if gem.comment -%>
-
-# <%= gem.comment %>
-<% end -%>
-<%= gem.commented_out ? "# " : "" %>gem "<%= gem.name %>"<%= %(, "#{gem.version}") if gem.version -%>
-<% if gem.options.any? -%>
-, <%= gem.options.map { |k,v|
-  "#{k}: #{v.inspect}" }.join(", ") %>
-<% end -%>
+<% gemfile_entries.each do |gemfile_entry| -%>
+<%= gemfile_entry %>
 <% end -%>
 
 <% end -%>

railties/test/generators/db_system_change_generator_test.rb

@@ -11,9 +11,10 @@ module Rails
           include GeneratorsTestHelper
 
           setup do
-            copy_gemfile(
-              GemfileEntry.new("sqlite3", nil, "Use sqlite3 as the database for Active Record")
-            )
+            copy_gemfile <<~ENTRY
+              # Use sqlite3 as the database for Active Record
+              gem 'sqlite3'
+            ENTRY
           end
 
           test "change to invalid database" do

railties/test/generators/generators_test_helper.rb

@@ -20,12 +20,6 @@ module GeneratorsTestHelper
   include ActiveSupport::Testing::Stream
   include ActiveSupport::Testing::MethodCallAssertions
 
-  GemfileEntry = Struct.new(:name, :version, :comment, :options, :commented_out) do
-    def initialize(name, version, comment, options = {}, commented_out = false)
-      super
-    end
-  end
-
   def self.included(base)
     base.class_eval do
       destination File.expand_path("../fixtures/tmp", __dir__)