ActionMailer: support overriding template name in multipart

Implicit rendering in multipart blocks now also uses the template
name from the options hash instead of always using the action name.

So you can now write

    mail(template_name: template_name) do |format|
      format.text
      format.html
    end

actionmailer/CHANGELOG.md

@@ -1,3 +1,8 @@
+*   Mails with multipart `format` blocks with implicit render now also check for
+    a template name in options hash instead of only using the action name.
+
+    *Marcus Ilgner*
+
 *   `config.force_ssl = true` will set
     `config.action_mailer.default_url_options = { protocol: 'https' }`
 

actionmailer/lib/action_mailer/base.rb

@@ -893,9 +893,7 @@ def assign_headers_to_message(message, headers)
 
     def collect_responses(headers)
       if block_given?
-        collector = ActionMailer::Collector.new(lookup_context) { render(action_name) }
-        yield(collector)
-        collector.responses
+        collect_responses_from_block(headers, &Proc.new)
       elsif headers[:body]
         [{
           body: headers.delete(:body),
@@ -906,6 +904,13 @@ def collect_responses(headers)
       end
     end
 
+    def collect_responses_from_block(headers)
+      templates_name = headers[:template_name] || action_name
+      collector = ActionMailer::Collector.new(lookup_context) { render(templates_name) }
+      yield(collector)
+      collector.responses
+    end
+
     def collect_responses_from_templates(headers)
       templates_path = headers[:template_path] || self.class.mailer_name
       templates_name = headers[:template_name] || action_name

actionmailer/test/base_test.rb

@@ -539,6 +539,12 @@ def welcome
     assert_equal("TEXT Implicit Multipart", mail.text_part.body.decoded)
   end
 
+  test "you can specify a different template for multipart render" do
+    mail = BaseMailer.implicit_different_template_with_block('explicit_multipart_templates').deliver
+    assert_equal("HTML Explicit Multipart Templates", mail.html_part.body.decoded)
+    assert_equal("TEXT Explicit Multipart Templates", mail.text_part.body.decoded)
+  end
+
   test "should raise if missing template in implicit render" do
     assert_raises ActionView::MissingTemplate do
       BaseMailer.implicit_different_template('missing_template').deliver_now

actionmailer/test/mailers/base_mailer.rb

@@ -104,6 +104,13 @@ def implicit_different_template(template_name='')
     mail(template_name: template_name)
   end
 
+  def implicit_different_template_with_block(template_name='')
+    mail(template_name: template_name) do |format|
+      format.text
+      format.html
+    end
+  end
+
   def explicit_different_template(template_name='')
     mail do |format|
       format.text { render template: "#{mailer_name}/#{template_name}" }