Ensures that Rails options are split by whitespace when generating Rails 6.y.z apps

Gemfile

@@ -4,3 +4,12 @@ source 'https://rubygems.org'
 gemspec
 
 gem 'rails', ENV['RAILS_VERSION'] if ENV['RAILS_VERSION']
+
+case ENV['RAILS_VERSION']
+when /^6\./
+  # This will only be necessary until release 6.0.1 is published (please see 
+  # https://github.com/rails/rails/issues/36954#issuecomment-522171807)
+  gem 'sass-rails', '~> 6.0'
+when /^5\./
+  gem 'sprockets', '~> 3.7'
+end

Rakefile

@@ -19,7 +19,17 @@ task :generate_test_gem => ['engine_cart:setup'] do
   require "rails/generators/rails/plugin/plugin_generator"
 
   pwd = Dir.pwd
-  Rails::Generators::PluginGenerator.start ['internal_test_gem']
+  generator_args = ['internal_test_gem']
+  generator_args << '--skip-javascript' if ENV.fetch('RAILS_VERSION', '') >= '6.0'
+
+  Rails::Generators::PluginGenerator.start generator_args
+
+  if Rails.version.to_f < 6.0 || Rails.version.to_f == 6.0
+    gemspec_file_path = "#{pwd}/internal_test_gem/.engine_cart.yml"
+    File.open(gemspec_file_path, 'w') do |f|
+      f.write('rails_options: "--skip-javascript"')
+    end
+  end
 
   Dir.chdir(pwd)
 
@@ -30,6 +40,14 @@ task :generate_test_gem => ['engine_cart:setup'] do
   IO.write(".internal_test_gem/internal_test_gem.gemspec", File.open(".internal_test_gem/internal_test_gem.gemspec") {|f| f.read.gsub(/.*homepage.*/, "")})
   IO.write(".internal_test_gem/internal_test_gem.gemspec", File.open(".internal_test_gem/internal_test_gem.gemspec") {|f| f.read.gsub(/.*sqlite3.*/, "")})
 
+  if Rails.version.to_f < 6.0 || Rails.version.to_f == 6.0
+    gemspec_file_path = ".internal_test_gem/internal_test_gem.gemspec"
+    IO.write(gemspec_file_path,
+             File.open(gemspec_file_path) { |f|
+                f.read.gsub(/(spec.add_dependency "rails".+$)/, "\\1\n  spec.add_dependency 'sprockets', '~> 3.7'")
+             })
+  end
+
   Rake::Task['engine_cart:inject_gemfile_extras'].invoke
   EngineCart.within_test_app do
     system "git init"
@@ -56,6 +74,7 @@ task :generate_test_gem => ['engine_cart:setup'] do
 
     system("bundle exec rake engine_cart:prepare")
     Bundler.clean_system "bundle install --quiet"
+    system("bundle update --conservative sprockets")
   end
 end
 

lib/engine_cart/configuration.rb

@@ -51,7 +51,11 @@ def templates_path
     ##
     # Additional options when generating a test rails application
     def rails_options
-      Array(options[:rails_options])
+      rails_options_values = options.fetch(:rails_options)
+      return [] if rails_options_values.nil?
+
+      rails_options = parse_options(rails_options_values)
+      Array(rails_options)
     end
 
     def extra_fingerprinted_files

spec/integration/engine_cart_spec.rb

@@ -31,6 +31,29 @@
     end
   end
 
+  if ENV.fetch('RAILS_VERSION', 0).to_f >= 6.0
+    context "when JavaScript support is disabled" do
+      before do
+        FileUtils.mv(".engine_cart.yml", ".engine_cart.yml.disabled")
+        FileUtils.cp(".engine_cart.yml.disabled", ".engine_cart.yml")
+
+        config_file = open(".engine_cart.yml", "a")
+        config_file.write(" --skip-javascript")
+        config_file.close
+      end
+
+      after do
+        FileUtils.rm(".engine_cart.yml")
+        FileUtils.mv(".engine_cart.yml.disabled", ".engine_cart.yml")
+      end
+
+      it "should not insert webpacker tools" do
+        `bundle exec rake engine_cart:generate`
+        expect(File).not_to exist(".internal_test_app/bin/yarn")
+      end
+    end
+  end
+
   it "should not recreate an existing rails app when the engine_cart:generate task is reinvoked" do
     EngineCart.within_test_app do
       `bundle exec rake engine_cart:generate`