rspec-mailer_matcher

An RSpec matcher that asserts a block delivers an ActionMailer message.

$ bundle add rspec-mailer_matcher --group test

Require the gem from spec_helper.rb or rails_helper.rb:

require 'rspec-mailer_matcher'

deliver then matches against the mail a block sends:

it 'emails the new user' do
  expect { SignUp.call(email: 'user@example.org') }
    .to deliver to: 'user@example.org', subject: 'Welcome'
end

It works with a subject block too:

subject { proc { SignUp.call(email: 'user@example.org') } }

it { is_expected.to deliver to: 'user@example.org' }

to, from and subject. to and from match when the address is among the recipients or the senders; subject has to be equal. Any other key raises ArgumentError rather than failing to match, so a typo cannot turn a not_to expectation green.

Every key given has to match the same mail, and the expectation passes when the block delivered at least one such mail.

When it fails, the matcher reports what the block delivered instead:

expected the block to deliver a mail with to: "carol@example.org", but the block delivered:
  to: ["alice@example.org"], from: ["app@example.org"], subject: "Welcome"

Delivery is read from ActionMailer::Base.deliveries, so the block has to deliver during the example. Mail enqueued with deliver_later is not seen unless the job runs inline.

Ruby 3.3 or newer, ActionMailer 8.0 or newer. The combinations covered by CI are listed in test.yml.

$ bin/setup            # install dependencies
$ bundle exec rake     # specs and RuboCop
$ bin/console          # IRB with the gem loaded

To run against one ActionMailer series:

$ BUNDLE_GEMFILE=gemfiles/actionmailer_8.0.gemfile bundle exec rake

Run the Release workflow and choose a bump. It updates version.rb, tags and pushes, publishes a GitHub release, and pushes the gem to RubyGems.org through trusted publishing.

Bug reports and pull requests are welcome at https://github.com/d-mato/rspec-mailer_matcher.

Available as open source under the terms of the MIT License.