refactor how adapters save response params to env

Ensures :response_headers always get initialized

Closes #50

lib/faraday/adapter.rb

@@ -31,8 +31,13 @@ module Faraday
       end
     end
 
-    def response_headers(env)
-      env[:response_headers] ||= Utils::Headers.new
+    def save_response(env, status, body, headers = nil)
+      env[:status] = status
+      env[:body] = body
+      env[:response_headers] = Utils::Headers.new.tap do |response_headers|
+        response_headers.update headers unless headers.nil?
+        yield response_headers if block_given?
+      end
     end
   end
 end

lib/faraday/adapter/action_dispatch.rb

@@ -21,8 +21,7 @@ module Faraday
         super
         @session.__send__(env[:method], env[:url].request_uri, env[:body], env[:request_headers])
         resp = @session.response
-        env.update :status => resp.status, :body => resp.body
-        response_headers(env).update resp.headers
+        save_response(env, resp.status, resp.body, resp.headers)
         @app.call env
       end
     end

lib/faraday/adapter/em_synchrony.rb

@@ -51,10 +51,11 @@ module Faraday
           client = block.call
         end
 
-        client.response_header.each do |name, value|
-          response_headers(env)[name.to_sym] = value
+        save_response(env, client.response_header.status, client.response) do |response_headers|
+          client.response_header.each do |name, value|
+            response_headers[name.to_sym] = value
+          end
         end
-        env.update :status => client.response_header.status, :body => client.response
 
         @app.call env
       rescue Errno::ECONNREFUSED

lib/faraday/adapter/excon.rb

@@ -17,8 +17,7 @@ module Faraday
           :headers => env[:request_headers],
           :body    => env[:body]
 
-        env.update :status => resp.status.to_i, :body => resp.body
-        response_headers(env).update resp.headers
+        save_response(env, resp.status.to_i, resp.body, resp.headers)
 
         @app.call env
       rescue ::Excon::Errors::SocketError

lib/faraday/adapter/net_http.rb

@@ -53,10 +53,11 @@ module Faraday
           raise Error::ConnectionFailed, $!
         end
 
-        http_response.each_header do |key, value|
-          response_headers(env)[key] = value
+        save_response(env, http_response.code.to_i, http_response.body) do |response_headers|
+          http_response.each_header do |key, value|
+            response_headers[key] = value
+          end
         end
-        env.update :status => http_response.code.to_i, :body => http_response.body
 
         @app.call env
       end

lib/faraday/adapter/patron.rb

@@ -21,8 +21,7 @@ module Faraday
           raise Error::ConnectionFailed, $!
         end
 
-        env.update :status => response.status, :body => response.body
-        response_headers(env).update response.headers
+        save_response(env, response.status, response.body, response.headers)
 
         @app.call env
       end

lib/faraday/adapter/test.rb

@@ -110,8 +110,7 @@ module Faraday
 
         if stub = stubs.match(env[:method], normalized_path, env[:body])
           status, headers, body = stub.block.call(env)
-          env.update :status => status, :body => body
-          response_headers(env).update headers
+          save_response(env, status, body, headers)
         else
           raise "no stubbed request for #{env[:method]} #{normalized_path} #{env[:body]}"
         end

lib/faraday/adapter/typhoeus.rb

@@ -27,8 +27,10 @@ module Faraday
 
         is_parallel = !!env[:parallel_manager]
         req.on_complete do |resp|
-          env.update :status => resp.code, :body => resp.body
-          response_headers(env).parse resp.headers
+          save_response(env, resp.code, resp.body) do |response_headers|
+            response_headers.parse resp.headers
+          end
+          # in async mode, :response is initialized at this point
           env[:response].finish(env) if is_parallel
         end