Use sass-rails in our test suite

Gemfile

@@ -12,6 +12,7 @@ gem 'mocha', '~> 0.14', require: false
 gem 'rack-cache', '~> 1.2'
 gem 'jquery-rails'
 gem 'coffee-rails'
+gem 'sass-rails'
 gem 'turbolinks', '~> 5'
 
 # require: false so bcrypt is loaded only when has_secure_password is used.

Gemfile.lock

@@ -264,6 +264,12 @@ GEM
       rufus-scheduler (~> 3.2)
     rubyzip (1.2.0)
     rufus-scheduler (3.2.1)
+    sass-rails (5.0.5)
+      railties (>= 4.0.0, < 6)
+      sass (~> 3.1)
+      sprockets (>= 2.8, < 4.0)
+      sprockets-rails (>= 2.0, < 4.0)
+      tilt (>= 1.1, < 3)
     sdoc (0.4.1)
       json (~> 1.7, >= 1.7.7)
       rdoc (~> 4.0)
@@ -308,6 +314,7 @@ GEM
     thor (0.19.1)
     thread (0.1.7)
     thread_safe (0.3.5)
+    tilt (2.0.5)
     turbolinks (5.0.0)
       turbolinks-source (~> 5)
     turbolinks-source (5.0.0)
@@ -374,6 +381,7 @@ DEPENDENCIES
   resque (< 1.26)
   resque-scheduler
   sass!
+  sass-rails
   sdoc (~> 0.4.0)
   sequel
   sidekiq

railties/test/application/assets_test.rb

@@ -188,7 +188,7 @@ module ApplicationTests
 
     test 'sprockets cache is not shared between environments' do
       app_file "app/assets/images/rails.png", "notactuallyapng"
-      app_file "app/assets/stylesheets/application.css.erb", "<%= asset_path('rails.png') %>"
+      app_file "app/assets/stylesheets/application.css.erb", "body { background: '<%= asset_path('rails.png') %>'; }"
       add_to_env_config 'production', 'config.assets.prefix = "production_assets"'
 
       precompile!