message-test.rb

# controller
class UsersController < ApplicationController
  def send_recovery
    user = User.find_by(email: params[:email].to_s.downcase)
    if user.nil?
      flash[:message] = t('email_not_found')
      redirect_to recover_form_users_path
    else
      send_recovery_code user
      redirect_to recover_users_path
    end
  end

  private

  def send_recovery_code(user)
    code = user.password_recovery
    CodeSender.password(code).deliver
  end
end

# spec
describe UsersController do
  context "post recover with existing email" do
    let(:user) { create(:confirmed_user) }

    it "sends password_recovery to user object" do
      expect(User).to receive(:find_by).with(email: user.email).and_return(user)
      post :send_recovery, email: user.email
      
      expect(user).to receive(:password_recovery)
    end
  end
end