ActionMailer testing with rspec

Question

I am developing a Rails 4 application which involves sending / receiving emails. For example, I send emails during user registration, user comment, and other events in the app.

I have created all emails using the action mailer, and I used rspec and shoulda for testing. I need to test if the mails are received correctly to the proper users. I don't know how to test the behavior.

Please show me how to test an ActionMailer using shoulda and rspec.

Solution

How to test ActionMailer with RSpec

• works for Rails 3 and 4
• this information has been taken from a good tutorial

Assuming the following Notifier mailer and User model:

class Notifier < ActionMailer::Base
  default from: '[email protected]'

  def instructions(user)
    @name = user.name
    @confirmation_url = confirmation_url(user)
    mail to: user.email, subject: 'Instructions'
  end
end

class User
  def send_instructions
    Notifier.instructions(self).deliver
  end
end

And the following test configuration:

# config/environments/test.rb
AppName::Application.configure do
  config.action_mailer.delivery_method = :test
end

These specs should get you what you want:

# spec/models/user_spec.rb
require 'spec_helper'

describe User do
  let(:user) { User.make }

  it "sends an email" do
    expect { user.send_instructions }.to change { ActionMailer::Base.deliveries.count }.by(1)
  end
end

# spec/mailers/notifier_spec.rb
require 'spec_helper'

describe Notifier do
  describe 'instructions' do
    let(:user) { mock_model User, name: 'Lucas', email: '[email protected]' }
    let(:mail) { Notifier.instructions(user) }

    it 'renders the subject' do
      expect(mail.subject).to eql('Instructions')
    end

    it 'renders the receiver email' do
      expect(mail.to).to eql([user.email])
    end

    it 'renders the sender email' do
      expect(mail.from).to eql(['[email protected]'])
    end

    it 'assigns @name' do
      expect(mail.body.encoded).to match(user.name)
    end

    it 'assigns @confirmation_url' do
      expect(mail.body.encoded).to match("http://aplication_url/#{user.id}/confirmation")
    end
  end
end

Props to Lucas Caton for the original blog post on this topic.

Comments

[Phillipp]

But that would not catch any problems if you, let's say catch an exception from the User.send_instructions and send yourself an email with the exception. You just test if any e-mail is sent, not your specific one.

[janechii]

@Phillipp made a good point, and if you'd like to test specific mail(s), ActionMailer::Base.deliveries is an array of Mail::Message objects. Refer to Mail::Message API.

[Aesthetic]

For those who wonder why mock_model doesn't work: stackoverflow.com/a/24060582/2899410

[glinda93]

For those who want to test deliver_later, check this post too: stackoverflow.com/a/42987726/11792577