Fix ContentEncoding handling of nil body.

Author: ioquatix

lib/protocol/http/content_encoding.rb

@@ -46,14 +46,16 @@ def call(request)
 				# https://lists.w3.org/Archives/Public/ietf-http-wg/2014JanMar/1179.html
 				return response if response.partial?
 
+				body = response.body
+				
+				# If there is no response body, there is nothing to encode:
+				return response if body.nil? or body.empty?
+				
 				# Ensure that caches are aware we are varying the response based on the accept-encoding request header:
 				response.headers.add("vary", "accept-encoding")
 
-				# TODO use http-accept and sort by priority
-				if !response.body.empty? and accept_encoding = request.headers["accept-encoding"]
+				if accept_encoding = request.headers["accept-encoding"]
 					if content_type = response.headers["content-type"] and @content_types =~ content_type
-						body = response.body
-						
 						accept_encoding.each do |name|
 							if wrapper = @wrappers[name]
 								response.headers["content-encoding"] = name

test/protocol/http/content_encoding.rb

@@ -79,4 +79,23 @@
 			expect(response.read).to be == "Hello World!"
 		end
 	end
+	
+	with "nil body" do
+		let(:app) do
+			app = ->(request){
+				Protocol::HTTP::Response[200, Protocol::HTTP::Headers["content-type" => "text/plain"], nil]
+			}
+		end
+			
+		let(:client) {subject.new(app)}
+		
+		it "does not compress response" do
+			response = client.get("/index", {"accept-encoding" => "gzip"})
+			
+			expect(response).to be(:success?)
+			expect(response.headers).not.to have_keys("content-encoding")
+			
+			expect(response.read).to be == nil
+		end
+	end
 end