AO3-6946 Fix manage collection items page sometimes showing unrelated works instead of bookmarks (#5114)

* AO3-6946 Add failing test for incorrect preload by includes

* AO3-6946 Fix incorrect preload by include_for_works

* Rubocop

Author: Bilka2

app/models/collection_item.rb

@@ -32,7 +32,7 @@ def collection_is_open
     end
   end
 
-  scope :include_for_works, -> { includes(work: :pseuds)}
+  scope :include_for_works, -> { includes(item: :pseuds) }
   scope :unrevealed, -> { where(unrevealed: true) }
   scope :anonymous, -> { where(anonymous:  true) }
 

spec/models/collection_item_spec.rb

@@ -77,4 +77,19 @@
       end
     end
   end
+
+  describe "include_for_works scope" do
+    let(:collection) { create(:collection) }
+    let(:work) { create(:work, id: 63) }
+    let(:bookmark) { create(:bookmark, id: 63) }
+
+    before { bookmark.collections << collection }
+
+    it "returns the correct type item for bookmarks" do
+      expect(work.id).to eq(bookmark.id)
+      expect(collection.collection_items).not_to be_empty
+      expect(collection.collection_items.first.item_type).to eq("Bookmark")
+      expect(collection.collection_items.include_for_works.first.item_type).to eq("Bookmark")
+    end
+  end
 end