Implement respond_to_missing? in the Parameterized::Mailer class

2 files changed, 25 insertions, 6 deletions

diff --git a/actionmailer/lib/action_mailer/parameterized.rb b/actionmailer/lib/action_mailer/parameterized.rb
index 7fa9da1724..73d98c198d 100644
--- a/actionmailer/lib/action_mailer/parameterized.rb
+++ b/actionmailer/lib/action_mailer/parameterized.rb
@@ -103,13 +103,18 @@ module ActionMailer
         @mailer, @params = mailer, params
       end
 
-      def method_missing(method_name, *args)
-        if @mailer.action_methods.include?(method_name.to_s)
-          ActionMailer::Parameterized::MessageDelivery.new(@mailer, method_name, @params, *args)
-        else
-          super
+      private
+        def method_missing(method_name, *args)
+          if @mailer.action_methods.include?(method_name.to_s)
+            ActionMailer::Parameterized::MessageDelivery.new(@mailer, method_name, @params, *args)
+          else
+            super
+          end
+        end
+
+        def respond_to_missing?(method, include_all = false)
+          @mailer.respond_to?(method, include_all)
         end
-      end
     end
 
     class MessageDelivery < ActionMailer::MessageDelivery # :nodoc:
diff --git a/actionmailer/test/parameterized_test.rb b/actionmailer/test/parameterized_test.rb
index f52945590b..fdfc20f785 100644
--- a/actionmailer/test/parameterized_test.rb
+++ b/actionmailer/test/parameterized_test.rb
@@ -38,4 +38,18 @@ class ParameterizedTest < ActiveSupport::TestCase
       @mail.deliver_later
     end
   end
+
+  test "respond_to?" do
+    mailer = ParamsMailer.with(inviter: "david@basecamp.com", invitee: "jason@basecamp.com")
+
+    assert_respond_to mailer, :invitation
+    assert_not_respond_to mailer, :anything
+
+    invitation = mailer.method(:invitation)
+    assert_equal Method, invitation.class
+
+    assert_raises(NameError) do
+      invitation = mailer.method(:anything)
+    end
+  end
 end