 = new tr.model.ScopedId('ptr', '0x1000');
      collection.idWasCreated(
          scopedId, 'tr.e.cc', 'Frame', 10);
      collection.idWasDeleted(
          scopedId, 'tr.e.cc', 'Frame', 15);
      collection.idWasCreated(
          scopedId, 'skia', 'TestObject', 20);
      collection.idWasDeleted(
          scopedId, 'skia', 'TestObject', 25);

      const testFrame = collection.getObjectInstanceAt(scopedId, 10);
      assert.instanceOf(testFrame, tr.model.ObjectInstance);
      assert.notInstanceOf(te