How to test ActionMailer + ActiveJob with Rspec (Example)

Suppose we have such email: class UserMailer < ApplicationMailer def welcome_email(user) @user = user mail(to: @user.email, subject: 'Welcome') end end That is delivered using default ActiveJob & ActionMailer's method: UserMailer.welcome_email(user).deliver_later. (you also need to set config.active_job.queue_adapter = :sidekiq [or some other adapter] in your application.rb to use deliver_later me