Ensure correct encoding on chunked responses

lib/rack/chunked.rb

@@ -23,6 +23,8 @@ def each
         @body.each do |chunk|
           size = bytesize(chunk)
           next if size == 0
+
+          chunk = chunk.dup.force_encoding(Encoding::BINARY) if chunk.respond_to?(:force_encoding)
           yield [size.to_s(16), term, chunk, term].join
         end
         yield TAIL

test/spec_chunked.rb

@@ -23,6 +23,16 @@
     response.body.should.equal "0\r\n\r\n"
   end
 
+  should 'chunks encoded bodies properly' do
+    body = ["\uFFFEHello", " ", "World"].map {|t| t.encode("UTF-16LE") }
+    app  = lambda { |env| [200, {}, body] }
+    response = Rack::MockResponse.new(*Rack::Chunked.new(app).call(@env))
+    response.headers.should.not.include 'Content-Length'
+    response.headers['Transfer-Encoding'].should.equal 'chunked'
+    response.body.encoding.to_s.should == "ASCII-8BIT"
+    response.body.should.equal "c\r\n\xFE\xFFH\x00e\x00l\x00l\x00o\x00\r\n2\r\n \x00\r\na\r\nW\x00o\x00r\x00l\x00d\x00\r\n0\r\n\r\n"
+  end if RUBY_VERSION >= "1.9"
+
   should 'not modify response when Content-Length header present' do
     app = lambda { |env| [200, {'Content-Length'=>'12'}, ['Hello', ' ', 'World!']] }
     status, headers, body = Rack::Chunked.new(app).call(@env)