Set asset mtime to the most recent source file mtime

lib/sprockets/asset.rb

@@ -2,12 +2,13 @@
 
 module Sprockets
   class Asset
-    attr_reader :environment, :source_paths, :source
+    attr_reader :environment, :source_paths, :source, :mtime
 
     def initialize(environment, source_file)
       @environment  = environment
       @source_paths = []
       @source       = ""
+      @mtime        = source_file.mtime
       require(source_file)
     end
 
@@ -30,6 +31,10 @@ def process_source(source_file)
       processor = Processor.new(environment, source_file)
       result    = ""
 
+      if source_file.mtime > mtime
+        @mtime = source_file.mtime
+      end
+
       processor.required_files.each { |file| require(file) }
       result << source_file.header
       processor.included_files.each { |file| result << process(file) }
@@ -59,11 +64,6 @@ def etag
       %("#{md5}")
     end
 
-    # TODO
-    def created_at
-      Time.now
-    end
-
     # TODO
     def stale?
       true

lib/sprockets/server.rb

@@ -85,7 +85,7 @@ def not_found_response
       end
 
       def not_modified?(asset, env)
-        env["HTTP_IF_MODIFIED_SINCE"] == asset.created_at.httpdate
+        env["HTTP_IF_MODIFIED_SINCE"] == asset.mtime.httpdate
       end
 
       def etag_match?(asset, env)
@@ -106,7 +106,7 @@ def headers(asset, env)
           headers["Content-Length"] = asset.length.to_s
 
           headers["Cache-Control"]  = "public, must-revalidate"
-          headers["Last-Modified"]  = asset.created_at.httpdate
+          headers["Last-Modified"]  = asset.mtime.httpdate
           headers["ETag"]           = asset.etag
 
           if env["QUERY_STRING"] == asset.md5