Clear url helper methods when routes are reloaded

Remove all the old url helper methods when clear! is called on the
route set because it's possible that some routes have been removed.

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.
 

actionpack/lib/action_dispatch/routing/route_set.rb

@@ -130,6 +130,12 @@ def helper_names
         end
 
         def clear!
+          @helpers.each do |helper|
+            @module.module_eval do
+              remove_possible_method helper
+            end
+          end
+
           @routes.clear
           @helpers.clear
         end

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

railties/test/application/routing_test.rb

@@ -277,6 +277,77 @@ def baz
       end
     end
 
+    test 'routes are added and removed when reloading' do
+      app('development')
+
+      controller :foo, <<-RUBY
+        class FooController < ApplicationController
+          def index
+            render text: "foo"
+          end
+        end
+      RUBY
+
+      controller :bar, <<-RUBY
+        class BarController < ApplicationController
+          def index
+            render text: "bar"
+          end
+        end
+      RUBY
+
+      app_file 'config/routes.rb', <<-RUBY
+        AppTemplate::Application.routes.draw do
+          get 'foo', to: 'foo#index'
+        end
+      RUBY
+
+      get '/foo'
+      assert_equal 'foo', last_response.body
+      assert_equal '/foo', Rails.application.routes.url_helpers.foo_path
+
+      get '/bar'
+      assert_equal 404, last_response.status
+      assert_raises NoMethodError do
+        assert_equal '/bar', Rails.application.routes.url_helpers.bar_path
+      end
+
+      app_file 'config/routes.rb', <<-RUBY
+        AppTemplate::Application.routes.draw do
+          get 'foo', to: 'foo#index'
+          get 'bar', to: 'bar#index'
+        end
+      RUBY
+
+      Rails.application.reload_routes!
+
+      get '/foo'
+      assert_equal 'foo', last_response.body
+      assert_equal '/foo', Rails.application.routes.url_helpers.foo_path
+
+      get '/bar'
+      assert_equal 'bar', last_response.body
+      assert_equal '/bar', Rails.application.routes.url_helpers.bar_path
+
+      app_file 'config/routes.rb', <<-RUBY
+        AppTemplate::Application.routes.draw do
+          get 'foo', to: 'foo#index'
+        end
+      RUBY
+
+      Rails.application.reload_routes!
+
+      get '/foo'
+      assert_equal 'foo', last_response.body
+      assert_equal '/foo', Rails.application.routes.url_helpers.foo_path
+
+      get '/bar'
+      assert_equal 404, last_response.status
+      assert_raises NoMethodError do
+        assert_equal '/bar', Rails.application.routes.url_helpers.bar_path
+      end
+    end
+
     test 'resource routing with irregular inflection' do
       app_file 'config/initializers/inflection.rb', <<-RUBY
         ActiveSupport::Inflector.inflections do |inflect|