Import preprocessor so @import'ed less files are automatic asset depe…

…ndencies. Fixes metaskills#3.

CHANGELOG.md

@@ -1,6 +1,11 @@
 CHANGELOG
 =========
 
+2.0.4 - 
+------------------
+* Import preprocessor so @import'ed less files are automatic asset dependencies. Fixes #3.
+
+
 2.0.3 - 11/13/2011
 ------------------
 * Add generator support. Fixes #8.

lib/less/rails.rb

@@ -12,5 +12,6 @@ module Rails
 require 'less/rails/version'
 require 'less/rails/helpers'
 require 'less/rails/template_handlers'
+require 'less/rails/import_processor'
 require 'less/rails/css_compressor'
 require 'less/rails/railtie'

lib/less/rails/import_processor.rb

@@ -0,0 +1,23 @@
+module Less  
+  module Rails    
+    class ImportProcessor < Tilt::Template
+
+      IMPORT_SCANNER = /@import\s*['"]([^'"]+)['"]\s*;/.freeze
+
+      def prepare
+      end
+
+      def evaluate(context, locals, &block)
+        import_paths = data.scan(IMPORT_SCANNER).flatten.compact.uniq
+        import_paths.each do |path|
+          asset = context.environment[path]
+          if asset && asset.pathname.to_s.ends_with?('.less')
+            context.depend_on_asset(asset.pathname)
+          end
+        end
+        data
+      end
+
+    end
+  end
+end

lib/less/rails/railtie.rb

@@ -20,6 +20,7 @@ module LessContext
 
       initializer 'less-rails.before.load_config_initializers', :before => 'load_config_initializers', :group => :all do |app|
         raise 'The less-rails plugin requires the asset pipeline to be enabled.' unless app.config.assets.enabled
+        app.assets.register_preprocessor 'text/css', ImportProcessor
       end
 
       initializer 'less-rails.after.load_config_initializers', :after => 'load_config_initializers', :group => :all do |app|

test/cases/basics_spec.rb

@@ -15,7 +15,12 @@ class BasicsSpec < Less::Rails::Spec
   end
 
   it 'must hook into less import so that imported paths are declared as sprocket dependencies of the source file' do
-    skip 'will need to use the basics asset, then change the frameworks/bootstrap/mixins.less file, then render basics again'
+    basics.must_match %r{#test-radiused\{border-radius:5px;\}}, 'default is 5px'
+    safely_edit_mixins do |d|
+      d.gsub! '5px', '10px'
+      File.open(mixins_asset.pathname,'w') { |f| f.write(d) }
+      basics.must_match %r{#test-radiused\{border-radius:10px;\}}, 'mixins.less should be a sprockets context dependency'
+    end
   end
 
   protected
@@ -24,4 +29,16 @@ def basics
     dummy_asset 'basics'
   end
 
+  def mixins_asset
+    dummy_assets['frameworks/bootstrap/mixins.less']
+  end
+
+  def safely_edit_mixins
+    data = File.read(mixins_asset.pathname)
+    begin
+      yield data.dup
+    ensure
+      File.open(mixins_asset.pathname,'w') { |f| f.write(data) }
+    end
+  end
 end

test/cases/railtie_spec.rb

@@ -34,6 +34,10 @@ class RailtieSpec < Less::Rails::Spec
       dummy_assets.context_class.less_config.must_equal dummy_config.less
     end
 
+    it 'must register our import pre processor' do
+      dummy_assets.preprocessors['text/css'].must_include Less::Rails::ImportProcessor
+    end
+
   end