Fix spec failures in Rack::Deflator under 1.9

There were two issues here that

* String#length was used to determine the Content-Length
  resulting in off-by-one failures in expected length
  assertions.

* The specs were using body.to_s to convert bodies to Strings.
  In Ruby 1.8, #to_s is like #join; in Ruby 1.9, #to_s is like
  #inspect

lib/rack/deflater.rb

@@ -36,17 +36,19 @@ def call(env)
         mtime = headers.key?("Last-Modified") ?
           Time.httpdate(headers["Last-Modified"]) : Time.now
         body = self.class.gzip(body, mtime)
-        headers = headers.merge("Content-Encoding" => "gzip", "Content-Length" => body.length.to_s)
+        size = body.respond_to?(:bytesize) ? body.bytesize : body.size
+        headers = headers.merge("Content-Encoding" => "gzip", "Content-Length" => size.to_s)
         [status, headers, [body]]
       when "deflate"
         body = self.class.deflate(body)
-        headers = headers.merge("Content-Encoding" => "deflate", "Content-Length" => body.length.to_s)
+        size = body.respond_to?(:bytesize) ? body.bytesize : body.size
+        headers = headers.merge("Content-Encoding" => "deflate", "Content-Length" => size.to_s)
         [status, headers, [body]]
       when "identity"
         [status, headers, body]
       when nil
-        message = ["An acceptable encoding for the requested resource #{request.fullpath} could not be found."]
-        [406, {"Content-Type" => "text/plain", "Content-Length" => message[0].length.to_s}, message]
+        message = "An acceptable encoding for the requested resource #{request.fullpath} could not be found."
+        [406, {"Content-Type" => "text/plain", "Content-Length" => message.length.to_s}, [message]]
       end
     end
 

test/spec_rack_deflater.rb

@@ -56,7 +56,7 @@ class << body; def each; yield("foo"); yield("bar"); end; end
       "Vary" => "Accept-Encoding",
     })
 
-    io = StringIO.new(response[2].to_s)
+    io = StringIO.new(response[2].join)
     gz = Zlib::GzipReader.new(io)
     gz.read.should.equal("foobar")
     gz.close
@@ -105,7 +105,7 @@ class << body; def each; yield("foo"); yield("bar"); end; end
       "Last-Modified" => last_modified
     })
 
-    io = StringIO.new(response[2].to_s)
+    io = StringIO.new(response[2].join)
     gz = Zlib::GzipReader.new(io)
     gz.read.should.equal("Hello World!")
     gz.close