For the following example we’re gonna use RSpec for the concise syntax for test doubles.

The remaining code is about permissions related logic: the edit link must be rendered only if the current user is an admin. This is tested by looking at the output of the template.

Notice that exposures includes an unused params key. While this is not strictly required, we recommend providing it since it’s expected by some standard view helpers (e.g. form helpers).

module Web
  module Views
    module Books
      class Show
        include Web::View
        def formatted_price
        end
        def edit_link
          if can_edit_book?
            link_to "Edit", routes.edit_book_path(id: book.id)
          end
        private
        def can_edit_book?
          current_user.admin?
        end
      end
    end
end