twitter: test fetching source data from direct image with referer.

test/functional/sources_controller_test.rb

@@ -3,10 +3,20 @@ require 'test_helper'
 class SourcesControllerTest < ActionController::TestCase
   context "The sources controller" do
     context "show action" do
-      should "work" do
+      should "work for a pixiv URL" do
         get :show, { url: "http://www.pixiv.net/member_illust.php?mode=medium&illust_id=14901720", format: "json" }
         assert_response :success
       end
+
+      should "work for a direct twitter URL with referer" do
+        get :show, {
+          url: "https://pbs.twimg.com/media/B4HSEP5CUAA4xyu.png:large",
+          ref: "https://twitter.com/nounproject/status/540944400767922176",
+          format: "json"
+        }
+
+        assert_response :success
+      end
     end
   end
 end