add a should_respond_with_content_type macro for controller tests to check content type of response

lib/shoulda/controller/helpers.rb

@@ -31,6 +31,10 @@ module ThoughtBot # :nodoc:
           variables_added
         }.map(&:to_s)
 
+        def response_content_type
+          @response.headers['Content-Type'] || @response.headers['type']
+        end
+
         def instantiate_variables_from_assigns(*names, &blk)
           old = {}
           names = (@response.template.assigns.keys - SPECIAL_INSTANCE_VARIABLES) if names.empty?

lib/shoulda/controller/macros.rb

@@ -134,6 +134,16 @@ module ThoughtBot # :nodoc:
           end
         end
 
+        # Macro that creates a test asserting that the response content type was 'content_type'.
+        # Example:
+        #
+        #   should_respond_with_content_type 'application/rss+xml'
+        def should_respond_with_content_type(content_type)
+          should "respond with content type of #{content_type}" do
+            assert_match content_type, response_content_type, "Expected #{content_type} but was actually #{response_content_type}"
+          end
+        end
+
         # Macro that creates a test asserting that the controller rendered the given template.
         # Example:
         #

test/functional/posts_controller_test.rb

@@ -48,6 +48,16 @@ class PostsControllerTest < Test::Unit::TestCase
       should_assign_to :user, :posts
       should_not_assign_to :foo, :bar
     end
+
+    context "viewing posts for a user with rss format" do
+      setup do
+        get :index, :user_id => users(:first), :format => 'rss'
+      end
+      should_respond_with :success
+      should_respond_with_content_type 'application/rss+xml'
+      should_assign_to :user, :posts
+      should_not_assign_to :foo, :bar
+    end
   end
 
 end

test/rails_root/app/controllers/posts_controller.rb

@@ -8,6 +8,10 @@ class PostsController < ApplicationController
     respond_to do |format|
       format.html # index.rhtml
       format.xml  { render :xml => @posts.to_xml }
+      format.rss do
+        headers['Content-Type'] = 'application/rss+xml'
+        head :ok
+      end
     end
   end