Include test helpers when ActionDispatch::IntegrationTest is loaded

As @dhh brings up, the point of `ActionDispatch::IntegrationTest` is to
allow users to test the integration of all the pieces called by a
controller. Asserting about the emails and jobs queued is part of that
task.

This commit includes the `ActionMailer::TestHelper` and
`ActiveJob::TestHelper` modules when the ActionMailer and ActiveJob
railties are initialized respectively.

1 files changed, 4 insertions, 0 deletions

diff --git a/activejob/lib/active_job/railtie.rb b/activejob/lib/active_job/railtie.rb
index d0294854d3..ecc0908d5f 100644
--- a/activejob/lib/active_job/railtie.rb
+++ b/activejob/lib/active_job/railtie.rb
@@ -30,6 +30,10 @@ module ActiveJob
           send(k, v) if respond_to? k
         end
       end
+
+      ActiveSupport.on_load(:action_dispatch_integration_test) do
+        include ActiveJob::TestHelper
+      end
     end
 
     initializer "active_job.set_reloader_hook" do |app|