appeals: crosspost appeals to deletion appeal thread.

Crosspost pending appeals to the deletion appeal thread. We do this once
per hour so we can batch together multiple appeals into one post.

test/unit/danbooru_maintenance_test.rb

@@ -38,4 +38,32 @@ class DanbooruMaintenanceTest < ActiveSupport::TestCase
       end
     end
   end
+
+  context "PostAppealForumUpdater" do
+    should "work when there are no pending appeals" do
+      assert_nothing_raised do
+        PostAppealForumUpdater.update_forum!
+      end
+    end
+
+    should "post pending appeals to the deletion appeal thread" do
+      @topic = as(create(:user)) { create(:forum_topic, title: PostAppealForumUpdater::APPEAL_TOPIC_TITLE) }
+      @appeal1 = create(:post_appeal, reason: "test")
+      @appeal2 = create(:post_appeal, reason: "")
+      @appeal3 = create(:post_appeal, created_at: 2.hours.ago)
+
+      PostAppealForumUpdater.update_forum!
+
+      assert_equal(@topic.id, ForumPost.last.topic_id)
+      assert_equal("post ##{@appeal1.post_id}: #{@appeal1.reason}\npost ##{@appeal2.post_id}", ForumPost.last.body)
+    end
+
+    should "create the deletion appeal thread if it doesn't already exist" do
+      @appeal = create(:post_appeal, reason: "")
+      PostAppealForumUpdater.update_forum!
+
+      assert_equal(PostAppealForumUpdater::APPEAL_TOPIC_TITLE, ForumPost.last.topic.title)
+      assert_equal("post ##{@appeal.post_id}", ForumPost.last.body)
+    end
+  end
 end