Test If deliver_later Is Called For A Mailer

There are many ways to test in your controller whether emails are going out. A concise and quick way to check is just to see if a deliver_later happened.

Depending on how your test environment is configured, this could look one of two ways.

If you have your queue_adapter set to :inline, then a deliver_later will happen synchronously. So, the email will immediately end up in the deliveries box.

expect {
  post :password_reset, params: valid_params
}.to change { ActionMailer::Base.deliveries.count }.by(1)

The behavior is a bit different if your queue_adapter is set to something like :test. In this case, the email is going to be queued in the app's job queue. Since it is not immediately being sent, the expectation will have to be about the job queue instead.

expect {
  post :password_reset, params: valid_params
}.to have_enqueued_job(ActionMailer::DeliveryJob)

We can even dig into more specifics like this:

expect {
  post :password_reset, params: valid_params
}.to have_enqueued_job(ActionMailer::DeliveryJob)
  .with('UserMailer', 'password_reset', 'deliver_later', Integer)