3 files changed, 94 insertions, 0 deletions
diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index 521b9b6835..31822f1eda 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -1,5 +1,7 @@
 ## Rails 4.0.0 (unreleased) ##
 
+*   Clear url helper methods when routes are reloaded. *Andrew White*
+
 *   Fix a bug in ActionDispatch::Request#raw_post that caused env['rack.input']
     to be read but not rewound.
 
diff --git a/actionpack/lib/action_dispatch/routing/route_set.rb b/actionpack/lib/action_dispatch/routing/route_set.rb
index 61071d1228..c11e66d110 100644
--- a/actionpack/lib/action_dispatch/routing/route_set.rb
+++ b/actionpack/lib/action_dispatch/routing/route_set.rb
@@ -130,6 +130,12 @@ module ActionDispatch
         end
 
         def clear!
+          @helpers.each do |helper|
+            @module.module_eval do
+              remove_possible_method helper
+            end
+          end
+
           @routes.clear
           @helpers.clear
         end
diff --git a/actionpack/test/dispatch/routing/route_set_test.rb b/actionpack/test/dispatch/routing/route_set_test.rb
new file mode 100644
index 0000000000..d57b1a5637
--- /dev/null
+++ b/actionpack/test/dispatch/routing/route_set_test.rb
@@ -0,0 +1,86 @@
+require 'abstract_unit'
+
+module ActionDispatch
+  module Routing
+    class RouteSetTest < ActiveSupport::TestCase
+      class SimpleApp
+        def initialize(response)
+          @response = response
+        end
+
+        def call(env)
+          [ 200, { 'Content-Type' => 'text/plain' }, [response] ]
+        end
+      end
+
+      setup do
+        @set = RouteSet.new
+      end
+
+      test "url helpers are added when route is added" do
+        draw do
+          get 'foo', to: SimpleApp.new('foo#index')
+        end
+
+        assert_equal '/foo', url_helpers.foo_path
+        assert_raises NoMethodError do
+          assert_equal '/bar', url_helpers.bar_path
+        end
+
+        draw do
+          get 'foo', to: SimpleApp.new('foo#index')
+          get 'bar', to: SimpleApp.new('bar#index')
+        end
+
+        assert_equal '/foo', url_helpers.foo_path
+        assert_equal '/bar', url_helpers.bar_path
+      end
+
+      test "url helpers are updated when route is updated" do
+        draw do
+          get 'bar', to: SimpleApp.new('bar#index'), as: :bar
+        end
+
+        assert_equal '/bar', url_helpers.bar_path
+
+        draw do
+          get 'baz', to: SimpleApp.new('baz#index'), as: :bar
+        end
+
+        assert_equal '/baz', url_helpers.bar_path
+      end
+
+      test "url helpers are removed when route is removed" do
+        draw do
+          get 'foo', to: SimpleApp.new('foo#index')
+          get 'bar', to: SimpleApp.new('bar#index')
+        end
+
+        assert_equal '/foo', url_helpers.foo_path
+        assert_equal '/bar', url_helpers.bar_path
+
+        draw do
+          get 'foo', to: SimpleApp.new('foo#index')
+        end
+
+        assert_equal '/foo', url_helpers.foo_path
+        assert_raises NoMethodError do
+          assert_equal '/bar', url_helpers.bar_path
+        end
+      end
+
+      private
+        def clear!
+          @set.clear!
+        end
+
+        def draw(&block)
+          @set.draw(&block)
+        end
+
+        def url_helpers
+          @set.url_helpers
+        end
+    end
+  end
+end