register non supported formats to there own handler and return there contents as empty so sprokets requres do not have to be changed for work. This will report to STDOUT if the file has been skipped

lib/jasmine/headless.rb

@@ -2,6 +2,9 @@ require 'pathname'
 
 module Jasmine
   module Headless
+    
+    EXCLUDED_FORMATS = %w{less sass scss erb str}
+    
     autoload :CommandLine, 'jasmine/headless/command_line'
 
     autoload :CoffeeScriptCache, 'jasmine/headless/coffee_script_cache'
@@ -16,11 +19,14 @@ module Jasmine
     autoload :UniqueAssetList, 'jasmine/headless/unique_asset_list'
 
     autoload :TemplateWriter, 'jasmine/headless/template_writer'
+    
+    autoload :FileChecker, 'jasmine/headless/file_checker'
 
     autoload :CoffeeTemplate, 'jasmine/headless/coffee_template'
     autoload :JSTemplate, 'jasmine/headless/js_template'
     autoload :JSTTemplate, 'jasmine/headless/jst_template'
     autoload :CSSTemplate, 'jasmine/headless/css_template'
+    autoload :NilTemplate, 'jasmine/headless/nil_template'
 
     autoload :Report, 'jasmine/headless/report'
     autoload :ReportMessage, 'jasmine/headless/report_message'

lib/jasmine/headless/coffee_template.rb

@@ -3,11 +3,17 @@ require 'rainbow'
 
 module Jasmine::Headless
   class CoffeeTemplate < Tilt::Template
+    include Jasmine::Headless::FileChecker
+    
     self.default_mime_type = 'application/javascript'
 
     def prepare ; end
 
     def evaluate(scope, locals, &block)
+      if bad_format?(file)
+        alert_bad_format(file)
+        return ''
+      end
       begin
         cache = Jasmine::Headless::CoffeeScriptCache.new(file)
         source = cache.handle

lib/jasmine/headless/css_template.rb

@@ -2,11 +2,16 @@ require 'tilt/template'
 
 module Jasmine::Headless
   class CSSTemplate < Tilt::Template
+    include Jasmine::Headless::FileChecker
     self.default_mime_type = 'text/css'
 
     def prepare ; end
 
     def evaluate(scope, locals, &block)
+      if bad_format?(file)
+        alert_bad_format(file)
+        return ''
+      end
       file ? %{<link rel="stylesheet" href="#{file}" type="text/css" />} : data
     end
   end

lib/jasmine/headless/file_checker.rb

@@ -0,0 +1,10 @@
+module Jasmine::Headless::FileChecker
+  def bad_format?(file)
+    return if file.nil?
+    ::Jasmine::Headless::EXCLUDED_FORMATS.any? {|format| file.include?(".#{format}") }
+  end
+  
+  def alert_bad_format(file)
+    puts "[%s] %s: %s" % [ 'Skipping File'.color(:red), file.color(:yellow), "unsupported format".color(:white) ]
+  end
+end

lib/jasmine/headless/files_list.rb

@@ -6,6 +6,7 @@ require 'sprockets'
 require 'sprockets/engines'
 
 module Jasmine::Headless
+  
   class FilesList
     class << self
       def vendor_asset_paths
@@ -39,8 +40,8 @@ module Jasmine::Headless
 
         # ...and unregister ones we don't want/need
         Sprockets.instance_eval do
-          %w{less sass scss erb str}.each do |extension|
-            @engines.delete(".#{extension}")
+         EXCLUDED_FORMATS.each do |extension|
+            register_engine ".#{extension}", Jasmine::Headless::NilTemplate
           end
 
           register_engine '.coffee', Jasmine::Headless::CoffeeTemplate

lib/jasmine/headless/js_template.rb

@@ -2,11 +2,16 @@ require 'tilt/template'
 
 module Jasmine::Headless
   class JSTemplate < Tilt::Template
+    include Jasmine::Headless::FileChecker
     self.default_mime_type = 'application/javascript'
 
     def prepare ; end
 
     def evaluate(scope, locals, &block)
+      if bad_format?(file)
+        alert_bad_format(file)
+        return ''
+      end
       if data[%r{^<script type="text/javascript"}]
         data
       else

lib/jasmine/headless/jst_template.rb

@@ -2,7 +2,12 @@ require 'sprockets/jst_processor'
 
 module Jasmine::Headless
   class JSTTemplate < Sprockets::JstProcessor
+    include Jasmine::Headless::FileChecker
     def evaluate(*args)
+      if bad_format?(file)
+        alert_bad_format(file)
+        return ''
+      end
       %{<script type="text/javascript">#{super}</script>}
     end
   end

lib/jasmine/headless/nil_template.rb

@@ -0,0 +1,14 @@
+require 'tilt/template'
+require 'rainbow'
+
+module Jasmine::Headless
+  class NilTemplate < Tilt::Template
+    
+    def prepare ; end
+
+    def evaluate(scope, locals, &block)
+      return ''
+    end
+  end
+end
+

spec/integration/sprockets_spec.rb

@@ -4,8 +4,8 @@ describe 'sprockets' do
   it 'should pull in the code via sprockets' do
     files = %x{bin/jasmine-headless-webkit -l -j spec/jasmine/with_sprockets_includes/with_sprockets_includes.yml}
     $?.exitstatus.should == 0
-
     files.lines.to_a.should contain_in_order_in_file_list(
+      'assets/application.js.erb: unsupported format',
       'vendor/assets/javascripts/jquery.js',
       'templates/that.jst.ejs',
       'templates/this.jst',

spec/lib/jasmine/headless/file_checker_spec.rb

@@ -0,0 +1,22 @@
+require 'spec_helper'
+
+describe Jasmine::Headless::FileChecker do
+  include FakeFS::SpecHelpers
+  
+  let(:test_class) do
+    object = Object.new
+    object.class.send(:include, Jasmine::Headless::FileChecker)
+    object
+  end
+  
+  context "bad_format?" do
+    it "should return false wth correct format" do
+      test_class.bad_format?('foobar.js').should be_false
+    end
+    it "should return false wth wrong format" do
+      test_class.bad_format?('foobar.js.erb').should be_true
+    end
+  end
+  
+
+end

spec/lib/jasmine/headless/nil_template_spec.rb

@@ -0,0 +1,31 @@
+require 'spec_helper'
+
+describe Jasmine::Headless::NilTemplate do
+  include FakeFS::SpecHelpers
+
+  let(:template) { described_class.new(file) { data } }
+  let(:file) { 'file' }
+  let(:data) { '' }
+
+  subject { template.render }
+
+  before do
+    File.open(file, 'wb') if file
+  end
+
+  context "no file'" do
+    let(:file) { nil }
+
+    it { should == data }
+  end
+
+  context 'file' do
+    it { should == '' }
+  end
+
+  context 'script as first thing' do
+    let(:data) { '' }
+
+    it { should == data }
+  end
+end