Rspec test controller with chain methods

How can I test this code in my controller? My problem is with the wizard_incompleted? method

class ApplicantsController < ApplicationController
   def index
      @applicant = current_user.applicant
      @application = @applicant.applications.last


      if @application.wizard_incompleted?
         # some redirect
      end
   end 
end


describe "GET #index" do

   let(:application)    { double('application')}

   it "redirect to wizard if it is incompleted" do
      get :index
      allow_any_instance_of(application).to receive(:wizard_incompleted?).and_return(true)
      expect(response).to redirect_to(new_applicants_application_path)
   end
end