Ruby 1.9: fix encoding for test_file_stream

actionpack/test/controller/send_file_test.rb

@@ -4,7 +4,7 @@
 module TestFileUtils
   def file_name() File.basename(__FILE__) end
   def file_path() File.expand_path(__FILE__) end
-  def file_data() File.open(file_path, 'rb') { |f| f.read } end
+  def file_data() @data ||= File.open(file_path, 'rb') { |f| f.read } end
 end
 
 class SendFileController < ActionController::Base
@@ -60,6 +60,7 @@ def test_file_stream
       require 'stringio'
       output = StringIO.new
       output.binmode
+      output.string.force_encoding(file_data.encoding) if output.string.respond_to?(:force_encoding)
       assert_nothing_raised { response.body_parts.each { |part| output << part.to_s } }
       assert_equal file_data, output.string
     end