NoMethodError: undefined method `assert_emails' in controller test

Question

According to the Rails documentation, the method assert_emails allows to transform the syntax :

assert_difference ->{ ActionMailer::Base.deliveries.size }, +1 do
  post :method_that_should_send_email
end

to

assert_emails 1 do
  post :method_that_should_send_email
end

which I find much better, because I don't have to copy paste the long syntax every time.

However I get the following error in my controllers tests when using the above code:

NoMethodError: undefined method `assert_emails'

I assume this is because the method is only available in mailers tests.

Is there a way to make it available to controllers tests too? Is there a good reason why this is not available by default? Is there a better way to test that calling a specific route results in sending a email?

Thanks.

Answer 1

I've just had the same problem when trying to use assert_emails in a regular test (not an ActionMailer::TestCase).

The helpers started working when I included ActionMailer::TestHelper to my test class.

class FooTest < ActiveSupport::TestCase
  include ActionMailer::TestHelper

  test '...' do
    assert_no_emails do
      # ...
    end
  end
end

I believe that should work in your controller tests as well.