test.php

public function __construct(Book $bookModel, BookTransformer $transformer)
    {
        parent::__construct();

        $this->transmit = [
          'transformer' => $transformer,
          'model' => $bookModel,
        ];
    }

    /**
     * Show a list of Books.
     *
     * @param Request $request
     * @return mixed
     */
    public function index(Request $request)
    {

        return $this->respondWithPaginatedCollection();
        //defaults to this->transmit->model as the $optionalModelItem. The transformer is already set too in constructor
        return $this->respondWithPaginatedCollection($optionalModelItem);

        /* inside your respond with methods they will run
          $includes = $this->transmit->transformer->getEagerLoads($this->fractal->getRequestedIncludes());
          $items = $this->eagerLoadIncludes($this->transmit->model, $includes);
          $items = $this->applyParameters($items, request()->query);
        */

    }

One thing that might be a problem. In some controllers I end up using two transformers. For example: the Job controller. In the index and show methods I use the JobTransformer but in the store and update methods I use the JobBuilderTransformer.

Those could (and maybe should) be split into two different controllers: JobController and JobBuilderController. So maybe it is not something to worry about.

Maybe this even enforces keeping controllers focused on one task.