Testing protected and private methods in rspec

thing_controller.rb

class ThingController < ApplicationController do
  # ...
  protected
  
  def protected_thing
    'foo'
  end
  
  private
  
  def private_thing
    'bar'
  end
end

thing_controller_spec.rb

describe ThingController, type: controller do
  # ...
  describe '#protected_thing' do
    it { expect(subject.send(:protected_thing)).to eq 'foo'
  end
  
  describe '#private_thing' do
    it { expect(subject.send(:private_thing)).to eq 'bar'
  end
end