updated importer to validate that sprites are png files

lib/compass/sprite_importer.rb

@@ -3,6 +3,7 @@ module Compass
     attr_accessor :uri, :options
     VAILD_FILE_NAME = /\A#{Sass::SCSS::RX::IDENT}\Z/
     SPRITE_IMPORTER_REGEX = %r{((.+/)?([^\*.]+))/(.+?)\.png}
+    VALID_EXTENSIONS = ['.png']
     
     def self.load(uri, options)
       klass = Compass::SpriteImporter.new
@@ -89,6 +90,14 @@ module Compass
       end
     end
     
+    def validate_sprites!
+      files.each do |file|
+        unless VALID_EXTENSIONS.include? File.extname(file)
+          raise Compass::Error, "Invalid sprite extension only: #{VALID_EXTENSIONS.join(',')} images are allowed"
+        end
+      end
+    end
+    
     # Returns the sass options for this sprite
     def sass_options
       @sass_options ||= options.merge(:filename => name, :syntax => :scss, :importer => self)
@@ -96,6 +105,7 @@ module Compass
     
     # Returns a Sass::Engine for this sprite object
     def sass_engine
+      validate_sprites!
       Sass::Engine.new(content_for_images, sass_options)
     end
     

test/units/sprites/importer_test.rb

@@ -46,4 +46,21 @@ class ImporterTest < Test::Unit::TestCase
     assert_equal 'bar', @importer.sass_options[:foo]
   end
   
+  test "should fail givin bad sprite extensions" do
+    @images_src_path = File.join(File.dirname(__FILE__), '..', '..', 'fixtures', 'sprites', 'public', 'images')
+    file = StringIO.new("images_path = #{@images_src_path.inspect}\n")
+    Compass.add_configuration(file, "sprite_config")
+    importer = Compass::SpriteImporter.new(:uri => 'bad_extensions/*.jpg', :options => options)
+    begin
+      importer.sass_engine
+      assert false, "Somthing happened an invalid sprite file made it past validation"
+    rescue Compass::Error => e
+      assert e.message.include?('.png')
+    end
+  end
+  
+  def taredown
+    Compass.reset_configuration!
+  end
+  
 end