Migrate to Dart Sass from LibSass

.gitignore

@@ -2,6 +2,8 @@ tmp
 log
 /node_modules
 yarn-error.log
-public/assets
+/public/assets
+/app/assets/builds/*
+!/app/assets/builds/.keep
 coverage
 .bundle

Gemfile

@@ -5,14 +5,14 @@ ruby "~> 3.2.0"
 gem "rails", "7.1.2"
 
 gem "bootsnap", require: false
+gem "dartsass-rails"
 gem "gds-api-adapters"
 gem "govuk_app_config"
 gem "govuk_personalisation"
 gem "govuk_publishing_components"
 gem "jwt"
 gem "plek"
 gem "ratelimit"
-gem "sassc-rails"
 gem "slimmer"
 gem "sprockets-rails"
 gem "uglifier"

Gemfile.lock

@@ -101,6 +101,9 @@ GEM
     crack (0.4.5)
       rexml
     crass (1.0.6)
+    dartsass-rails (0.5.0)
+      railties (>= 6.0.0)
+      sass-embedded (~> 1.63)
     date (3.3.4)
     diff-lcs (1.5.0)
     docile (1.4.0)
@@ -109,7 +112,6 @@ GEM
       ruby2_keywords
     erubi (1.12.0)
     execjs (2.8.1)
-    ffi (1.15.5)
     gds-api-adapters (92.0.0)
       addressable
       link_header
@@ -546,14 +548,15 @@ GEM
     ruby-progressbar (1.13.0)
     ruby2_keywords (0.0.5)
     rubyzip (2.3.2)
-    sassc (2.4.0)
-      ffi (~> 1.9)
-    sassc-rails (2.1.2)
-      railties (>= 4.0.0)
-      sassc (>= 2.0)
-      sprockets (> 3.0)
-      sprockets-rails
-      tilt
+    sass-embedded (1.69.5)
+      google-protobuf (~> 3.23)
+      rake (>= 13.0.0)
+    sass-embedded (1.69.5-aarch64-linux-gnu)
+      google-protobuf (~> 3.23)
+    sass-embedded (1.69.5-arm64-darwin)
+      google-protobuf (~> 3.23)
+    sass-embedded (1.69.5-x86_64-linux-gnu)
+      google-protobuf (~> 3.23)
     selenium-webdriver (4.16.0)
       rexml (~> 3.2, >= 3.2.5)
       rubyzip (>= 1.2.2, < 3.0)
@@ -586,7 +589,6 @@ GEM
     statsd-ruby (1.5.0)
     stringio (3.1.0)
     thor (1.3.0)
-    tilt (2.0.10)
     timecop (0.9.8)
     timeout (0.4.1)
     tzinfo (2.0.6)
@@ -617,6 +619,7 @@ DEPENDENCIES
   bootsnap
   capybara
   climate_control
+  dartsass-rails
   gds-api-adapters
   govuk_app_config
   govuk_personalisation
@@ -630,7 +633,6 @@ DEPENDENCIES
   ratelimit
   rspec-rails
   rubocop-govuk
-  sassc-rails
   simplecov
   slimmer
   sprockets-rails

app/assets/config/manifest.js

@@ -1 +1,3 @@
 //= link application.js
+
+//= link_tree ../builds

config/application.rb

@@ -42,7 +42,5 @@ class Application < Rails::Application
     # to use CSS that has same function names as SCSS such as max.
     # https://github.com/alphagov/govuk-frontend/issues/1350
     config.assets.css_compressor = nil
-
-    config.assets.precompile << get_component_css_paths
   end
 end

config/environments/production.rb

@@ -27,9 +27,6 @@
   # Compress JS using a preprocessor.
   config.assets.js_compressor = :uglifier
 
-  # Compress CSS using a preprocessor.
-  # config.assets.css_compressor = :sass
-
   # Do not fallback to assets pipeline if a precompiled asset is missed.
   config.assets.compile = false
 

config/initializers/dartsass.rb

@@ -0,0 +1,6 @@
+APP_STYLESHEETS = {
+  "application.scss" => "application.css",
+}.freeze
+
+all_stylesheets = APP_STYLESHEETS.merge(GovukPublishingComponents::Config.all_stylesheets)
+Rails.application.config.dartsass.builds = all_stylesheets