Module specs

require 'rspec'

module Authenticable
  def current_user
    @current_user ||= 'Pedro'
  end

  def authenticate_with_token!
    render json: { errors: "Not authenticated" },
                status: :unauthorized unless user_signed_in?
  end

  def user_signed_in?
    current_user != nil
  end
end

class Authentication
  include Authenticable
end

RSpec.describe Authenticable do
  let(:authentication) { Authentication.new }
  subject { authentication }

  describe '.authenticate_with_token' do
    before do
      allow(authentication).to receive(:current_user).and_return(nil)
      allow(authentication).to receive(:render) do |args|
        args
      end
    end

    it 'returns error' do
      expect(authentication.authenticate_with_token![:json][:errors]).to eq 'Not authenticated'
    end

    it 'returns unauthorized status' do
      expect(authentication.authenticate_with_token![:status]).to eq :unauthorized
    end
  end
end