tests: add missing controller tests.

test/factories/pixiv_ugoira_frame_data.rb

@@ -0,0 +1,12 @@
+FactoryBot.define do
+  factory(:pixiv_ugoira_frame_data) do
+    post
+    content_type { "image/jpeg" }
+    data do
+      [
+        { "file" => "000000.jpg", "delay" => 200 },
+        { "file" => "000001.jpg", "delay" => 200 },
+      ]
+    end
+  end
+end