Support `Mailer.deliver_foo(*args)` as a synonym for `Mailer.foo(*args).deliver`.

This makes it easy to write e.g. `Mailer.expects(:deliver_foo)` when
testing code that calls the mailer.

actionmailer/CHANGELOG.md

@@ -1,5 +1,10 @@
 ## Rails 4.0.0 (unreleased) ##
 
+* Support `Mailer.deliver_foo(*args)` as a synonym for
+  `Mailer.foo(*args).deliver`. This makes it easy to write e.g.
+  `Mailer.expects(:deliver_foo)` when testing code that calls
+  the mailer. *Jon Leighton*
+
 * Allow delivery method options to be set per mail instance *Aditya Sanghi*
 
   If your smtp delivery settings are dynamic,

actionmailer/lib/action_mailer/base.rb

@@ -142,6 +142,7 @@ module ActionMailer
   # for delivery later:
   #
   #   Notifier.welcome(david).deliver # sends the email
+  #   Notifier.deliver_welcome(david) # synonym for the former
   #   mail = Notifier.welcome(david)  # => a Mail::Message object
   #   mail.deliver                    # sends the email
   #
@@ -487,6 +488,8 @@ module ActionMailer
       def method_missing(method_name, *args)
         if action_methods.include?(method_name.to_s)
           QueuedMessage.new(queue, self, method_name, *args)
+        elsif method_name.to_s =~ /^deliver_(.+)$/ && action_methods.include?($1)
+          public_send($1, *args).deliver
         else
           super
         end

actionmailer/test/base_test.rb

@@ -662,6 +662,13 @@ class BaseTest < ActiveSupport::TestCase
     assert_equal ["robert.pankowecki@gmail.com"], DefaultFromMailer.welcome.from
   end
 
+  test "Mailer.deliver_welcome calls Mailer.welcome.deliver" do
+    BaseMailer.deliveries.clear
+    BaseMailer.deliver_welcome(subject: 'omg')
+    assert_equal 1, BaseMailer.deliveries.length
+    assert_equal 'omg', BaseMailer.deliveries.first.subject
+  end
+
   protected
 
     # Execute the block setting the given values and restoring old values after