tests: add sources controller tests.

test/functional/sources_controller_test.rb

@@ -0,0 +1,12 @@
+require 'test_helper'
+
+class SourcesControllerTest < ActionController::TestCase
+  context "The sources controller" do
+    context "show action" do
+      should "work" do
+        get :show, { url: "http://www.pixiv.net/member_illust.php?mode=medium&illust_id=14901720", format: "json" }
+        assert_response :success
+      end
+    end
+  end
+end