Merge pull request #3136 from guilleiguaran/clear-digests-on-precompile

Avoid use of existing precompiled assets during rake assets:precompile run

actionpack/lib/sprockets/assets.rake

@@ -25,6 +25,10 @@ namespace :assets do
 
       env    = Rails.application.assets
 
+      # Always compile files and avoid use of existing precompiled assets
+      config.assets.compile = true
+      config.assets.digests = {}
+
       target = File.join(Rails.public_path, config.assets.prefix)
       static_compiler = Sprockets::StaticCompiler.new(env, target, :digest => config.assets.digest)
 

railties/test/application/assets_test.rb

@@ -256,6 +256,24 @@ module ApplicationTests
       assert_match(/\/assets\/rails-([0-z]+)\.png/, File.read(file))
     end
 
+    test "precompile shouldn't use the digests present in manifest.yml" do
+      app_file "app/assets/stylesheets/application.css.erb", "<%= asset_path('rails.png') %>"
+
+      ENV["RAILS_ENV"] = "production"
+      precompile!
+
+      manifest = "#{app_path}/public/assets/manifest.yml"
+      assets = YAML.load_file(manifest)
+      asset_path = assets["application.css"]
+
+      app_file "app/assets/images/rails.png", "image changed"
+
+      precompile!
+      assets = YAML.load_file(manifest)
+
+      assert_not_equal asset_path, assets["application.css"]
+    end
+
     test "precompile appends the md5 hash to files referenced with asset_path and run in production as default even using RAILS_GROUPS=assets" do
       app_file "app/assets/stylesheets/application.css.erb", "<%= asset_path('rails.png') %>"
       add_to_config "config.assets.compile = true"