3 files changed, 44 insertions, 0 deletions
diff --git a/actionpack/lib/action_controller/metal/renderers.rb b/actionpack/lib/action_controller/metal/renderers.rb
index 5272dc6cdb..abed6e53cc 100644
--- a/actionpack/lib/action_controller/metal/renderers.rb
+++ b/actionpack/lib/action_controller/metal/renderers.rb
@@ -6,6 +6,13 @@ module ActionController
     Renderers.add(key, &block)
   end
 
+  class MissingRenderer < LoadError
+    def initialize(format)
+      @format = format
+      super("No renderer defined for format: #{@format}")
+    end
+  end
+
   module Renderers
     extend ActiveSupport::Concern
 
diff --git a/actionpack/lib/action_controller/metal/responder.rb b/actionpack/lib/action_controller/metal/responder.rb
index fd5b661209..66ff34a794 100644
--- a/actionpack/lib/action_controller/metal/responder.rb
+++ b/actionpack/lib/action_controller/metal/responder.rb
@@ -202,6 +202,7 @@ module ActionController #:nodoc:
     # This is the common behavior for formats associated with APIs, such as :xml and :json.
     def api_behavior(error)
       raise error unless resourceful?
+      raise MissingRenderer.new(format) unless has_renderer?
 
       if get?
         display resource
@@ -269,6 +270,11 @@ module ActionController #:nodoc:
       resource.respond_to?(:errors) && !resource.errors.empty?
     end
 
+    # Check whether the neceessary Renderer is available
+    def has_renderer?
+      Renderers::RENDERERS.include?(format)
+    end
+
     # By default, render the <code>:edit</code> action for HTML requests with errors, unless
     # the verb was POST.
     #
diff --git a/actionpack/test/controller/mime/respond_with_test.rb b/actionpack/test/controller/mime/respond_with_test.rb
index 582050b78c..29ddbff8d4 100644
--- a/actionpack/test/controller/mime/respond_with_test.rb
+++ b/actionpack/test/controller/mime/respond_with_test.rb
@@ -107,6 +107,20 @@ class RenderJsonRespondWithController < RespondWithController
   end
 end
 
+class CsvRespondWithController < ActionController::Base
+  respond_to :csv
+
+  class RespondWithCsv
+    def to_csv
+      "c,s,v"
+    end
+  end
+
+  def index
+    respond_with(RespondWithCsv.new)
+  end
+end
+
 class EmptyRespondWithController < ActionController::Base
   def index
     respond_with(Customer.new("david", 13))
@@ -607,6 +621,23 @@ class RespondWithControllerTest < ActionController::TestCase
     RespondWithController.responder = ActionController::Responder
   end
 
+  def test_uses_renderer_if_an_api_behavior
+    ActionController::Renderers.add :csv do |obj, options|
+      send_data obj.to_csv, type: Mime::CSV
+    end
+    @controller = CsvRespondWithController.new
+    get :index, format: 'csv'
+    assert_equal Mime::CSV, @response.content_type
+    assert_equal "c,s,v", @response.body
+  end
+
+  def test_raises_missing_renderer_if_an_api_behavior_with_no_renderer
+    @controller = CsvRespondWithController.new
+    assert_raise ActionController::MissingRenderer do
+      get :index, format: 'csv'
+    end
+  end
+
   def test_error_is_raised_if_no_respond_to_is_declared_and_respond_with_is_called
     @controller = EmptyRespondWithController.new
     @request.accept = "*/*"