Support chaining of ERB for Sprockets 4 (#191)

* fix CI failures due to usage of Rack 3

Author: ashkulz

Gemfile

@@ -2,6 +2,7 @@ source 'https://rubygems.org'
 
 gemspec
 
+gem "rack", "~> 2" # Rack 3 is not compatible with Jasmine and fails -- jasmine-3.99.0/lib/jasmine/server.rb:12:in `start': uninitialized constant Rack::Server (NameError)
 gem "rails", "~> #{ENV['RAILS_VER'] || raise("missing rails version")}"
 gem "sprockets", "~> #{ENV['SPROCKETS_VER'] || raise("missing sprockets version")}"
 

lib/haml_coffee_assets/rails/engine.rb

@@ -38,6 +38,9 @@ class Engine < ::Rails::Engine
             env.register_mime_type 'text/hamlc', extensions: ['.hamlc', '.jst.hamlc']
             env.register_transformer 'text/hamlc', 'application/javascript', ::HamlCoffeeAssets::Transformer
             env.register_transformer 'text/hamlc', 'application/javascript+function', ::HamlCoffeeAssets::Transformer
+            # support for chaining via ERB, documented via https://github.com/rails/sprockets/pull/807
+            env.register_mime_type 'text/hamlc+ruby', extensions: ['.hamlc.erb', '.jst.hamlc.erb']
+            env.register_transformer 'text/hamlc+ruby', 'text/hamlc', ::Sprockets::ERBProcessor
           end
 
           if env.respond_to?(:register_engine)