Use the Sass cache to store information about sprites across compiles -- this removes one aspect of lemonade's filesystem dependency.

lib/compass/sass_extensions/monkey_patches/sprites.rb

@@ -7,7 +7,7 @@ module Sass
       alias_method :render_without_sprites, :render
       def render
         if result = render_without_sprites
-          Compass::Sprites.generate_sprites
+          Compass::Sprites.generate_sprites(options)
           result = ERB.new(result).result(binding)
           Compass::Sprites.reset
           return result

lib/compass/sprites.rb

@@ -31,30 +31,29 @@ module Compass::Sprites
       @@sprites = {}
     end
 
-    def generate_sprites
+    def generate_sprites(options)
       sprites.each do |sprite_name, sprite|
         calculate_sprite sprite
-        if sprite_changed?(sprite_name, sprite)
+        if sprite_changed?(sprite_name, sprite, options)
           generate_sprite_image sprite
-          remember_sprite_info! sprite_name, sprite
+          remember_sprite_info! sprite_name, sprite, options
         end
       end
     end
 
-    def sprite_changed?(sprite_name, sprite)
-      existing_sprite_info = YAML.load(File.read(sprite_info_file(sprite_name)))
+    def sprite_changed?(sprite_name, sprite, options)
+      existing_sprite_info = options[:cache_store].retrieve("_#{sprite_name}_data", "") || {}
       existing_sprite_info[:sprite] != sprite or existing_sprite_info[:timestamps] != timestamps(sprite)
     rescue
       true
     end
 
-    def remember_sprite_info!(sprite_name, sprite)
-      File.open(sprite_info_file(sprite_name), 'w') do |file|
-        file << {
-          :sprite => sprite,
-          :timestamps => timestamps(sprite),
-        }.to_yaml
-      end
+    def remember_sprite_info!(sprite_name, sprite, options)
+      data = {
+        :sprite => sprite,
+        :timestamps => timestamps(sprite),
+      }
+      options[:cache_store].store("_#{sprite_name}_data", "", data)
     end
   
   private

spec/lemonade_spec.rb

@@ -20,45 +20,54 @@ describe Compass::Sprites do
   ###
 
   describe '#remember_sprite_info' do
+
     subject { Compass::Sprites }
 
-    it 'should save sprite info into a file' do
-      File.should_receive(:open).with(File.join('image_path', 'the_sprite.sprite_info.yml'), 'w').and_yield(@file)
-      @file.should_receive(:<<)
-      subject.remember_sprite_info!('the_sprite', @sprite)
+    before :each do
+      @options = {
+        :cache_store => Sass::InMemoryCacheStore.new
+      }
+    end
+
+    it 'should save sprite info to the sass cache' do
+      subject.remember_sprite_info!('the_sprite', @sprite, @options)
+      @options[:cache_store].retrieve('_the_sprite_data', "")[:sprite].should == @sprite
     end
   end
 
   ###
 
   describe '#sprite_changed?' do
+
     subject { Compass::Sprites }
 
+    before :each do
+      @options = {
+        :cache_store => Sass::InMemoryCacheStore.new
+      }
+    end
+
     it 'should be false if nothing changed' do
-      File.should_receive(:open).and_yield(@file)
-      subject.remember_sprite_info!('the sprite', @sprite)
-      subject.sprite_changed?('the sprite', @sprite).should be_false
+      subject.remember_sprite_info!('the sprite', @sprite, @options)
+      subject.sprite_changed?('the sprite', @sprite, @options).should be_false
     end
 
     it 'should be true if the sprite info has changed' do
-      File.should_receive(:open).and_yield(@file)
-      subject.remember_sprite_info!('the sprite', @sprite)
+      subject.remember_sprite_info!('the sprite', @sprite, @options)
       @sprite[:info] = 'changed info'
-      subject.sprite_changed?('the sprite', @sprite).should be_true
+      subject.sprite_changed?('the sprite', @sprite, @options).should be_true
     end
 
     it 'should be true if the images changed' do
-      File.should_receive(:open).and_yield(@file)
-      subject.remember_sprite_info!('the sprite', @sprite)
+      subject.remember_sprite_info!('the sprite', @sprite, @options)
       @sprite[:images] = []
-      subject.sprite_changed?('the sprite', @sprite).should be_true
+      subject.sprite_changed?('the sprite', @sprite, @options).should be_true
     end
 
     it 'should be true if a images timestamp changed' do
-      File.should_receive(:open).and_yield(@file)
-      subject.remember_sprite_info!('the sprite', @sprite)
+      subject.remember_sprite_info!('the sprite', @sprite, @options)
       File.stub!(:ctime => Time.now)
-      subject.sprite_changed?('the sprite', @sprite).should be_true
+      subject.sprite_changed?('the sprite', @sprite, @options).should be_true
     end
 
   end