ActionMailerMatchers provides you with RSpec one-liners that help you to test sending emails in your Rails application.

It is typical to test that an email has been delivered in a controller or service by doing the following:

expect { some_action.execute }.to change { 
  ActionMailer::Base.deliveries.count }.by(1)

However, this does not specify what email was sent and to where. ActionMailerMatchers solves this problem by providing the have_received_email matcher, which ensures that the passed email address or user (which must respond .email) was the email's “to” address. You may also use the optional subject and body arguments to check that content matches the email you were expecting to send.

expect("address@email.com").to have_received_email(body: "Wonderful email body")

expect(some_user).to have_received_email(subject: "My great subject") 

Check it out and feel free to contribute by opening an issue or pull request!