FIX: correctly infer polymorphic class from bookmarkable type

app/models/bookmark.rb

@@ -46,7 +46,8 @@ class Bookmark < ActiveRecord::Base
   validates :name, length: { maximum: 100 }
 
   def registered_bookmarkable
-    Bookmark.registered_bookmarkable_from_type(self.bookmarkable_type)
+    type = Bookmark.polymorphic_class_for(self.bookmarkable_type).name
+    Bookmark.registered_bookmarkable_from_type(type)
   end
 
   def polymorphic_columns_present

plugins/chat/spec/requests/core_ext/bookmarks_controller_spec.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+RSpec.describe BookmarksController do
+  let(:current_user) { Fabricate(:user) }
+  let(:bookmark_message) { Fabricate(:chat_message) }
+  let(:bookmark_user) { current_user }
+
+  before { sign_in(current_user) }
+
+  context "when bookmarking a chat message" do
+    describe "#create" do
+      it "creates the bookmark" do
+        post "/bookmarks.json",
+             params: {
+               bookmarkable_id: bookmark_message.id,
+               bookmarkable_type: "Chat::Message",
+               reminder_at: (Time.zone.now + 1.day).iso8601,
+             }
+
+        expect(response.status).to eq(200)
+        expect(Bookmark.find_by(bookmarkable: bookmark_message).user_id).to eq(current_user.id)
+      end
+    end
+
+    describe "#destroy" do
+      let!(:bookmark) { Fabricate(:bookmark, bookmarkable: bookmark_message, user: bookmark_user) }
+
+      it "destroys the bookmark" do
+        delete "/bookmarks/#{bookmark.id}.json"
+
+        expect(response.status).to eq(200)
+        expect(Bookmark.find_by(id: bookmark.id)).to eq(nil)
+      end
+    end
+  end
+end