diff --git a/Readme.md b/Readme.md
index 0559644..4f145b2 100644
--- a/Readme.md
+++ b/Readme.md
@@ -3,6 +3,8 @@ Autotest for Test::Unit on Rails, including plugins for migrations and fixtures.
  - independent of ZenTest
  - added tests
  - fixed namespace issues
+ - support application_controller.rb
+ - lib/foo/bar -> test/unit/foo/bar_test
 
 Install
 =======
diff --git a/lib/autotest/rails.rb b/lib/autotest/rails.rb
index 1e25783..822a25f 100644
--- a/lib/autotest/rails.rb
+++ b/lib/autotest/rails.rb
@@ -10,77 +10,91 @@ def initialize # :nodoc:
 
     clear_mappings
 
-    self.add_mapping(/^lib\/.*\.rb$/) do |filename, _|
-      impl = File.basename(filename, '.rb')
-      files_matching %r%^test/unit/#{impl}_test.rb$%
-      # TODO: (unit|functional|integration) maybe?
+    # lib/foo/bar.rb -> unit/foo/bar_test.rb
+    add_mapping %r%^lib/(.*)\.rb$% do |_, m|
+      "test/unit/#{m[1]}_test.rb"
     end
 
     add_mapping %r%^test/fixtures/(.*)s.yml% do |_, m|
-      ["test/unit/#{m[1]}_test.rb",
-       "test/controllers/#{m[1]}_controller_test.rb",
-       "test/views/#{m[1]}_view_test.rb",
-       "test/functional/#{m[1]}_controller_test.rb"]
+      [
+        "test/unit/#{m[1]}_test.rb",
+        "test/views/#{m[1]}_view_test.rb",
+        "test/controllers/#{m[1]}_controller_test.rb",
+        "test/functional/#{m[1]}_controller_test.rb"
+      ]
     end
 
-    add_mapping %r%^test/(unit|integration|controllers|views|functional)/.*rb$% do |filename, _|
+    # test changes -> run test
+    add_mapping %r%^test/(#{test_namespaces*'|'})/.*rb$% do |filename, _|
       filename
     end
 
+    # model -> unit
     add_mapping %r%^app/models/(.*)\.rb$% do |_, m|
       "test/unit/#{m[1]}_test.rb"
     end
 
+    # application_helper -> all views/helpers/controllers
     add_mapping %r%^app/helpers/application_helper.rb% do
-      files_matching %r%^test/(views|functional)/.*_test\.rb$%
+      files_matching %r%^test/(views|functional|helpers)/.*_test\.rb$%
     end
 
+    # helper -> helper + view + controllers
     add_mapping %r%^app/helpers/(.*)_helper.rb% do |_, m|
-      if m[1] == "application" then
-        files_matching %r%^test/(views|functional)/.*_test\.rb$%
-      else
-        ["test/views/#{m[1]}_view_test.rb",
-         "test/functional/#{m[1]}_controller_test.rb"]
-      end
+      [
+        "test/views/#{m[1]}_view_test.rb",
+        "test/helpers/#{m[1]}_helper_test.rb",
+        "test/functional/#{m[1]}_controller_test.rb",
+        "test/controllers/#{m[1]}_controller_test.rb",
+      ]
     end
 
+    # view -> view + controller
     add_mapping %r%^app/views/(.*)/% do |_, m|
-      ["test/views/#{m[1]}_view_test.rb",
-       "test/functional/#{m[1]}_controller_test.rb"]
+      [
+        "test/views/#{m[1]}_view_test.rb",
+        "test/functional/#{m[1]}_controller_test.rb",
+        "test/controllers/#{m[1]}_controller_test.rb"
+      ]
+    end
+
+    # application_controller.rb -> all views/controllers
+    add_mapping %r%^app/controllers/application_controller\.rb$% do |_, m|
+      files_matching %r%^test/(controllers|views|functional)/.*_test\.rb$%
     end
 
     add_mapping %r%^app/controllers/(.*)\.rb$% do |_, m|
-      if m[1] == "application" then
-        files_matching %r%^test/(controllers|views|functional)/.*_test\.rb$%
-      else
-        ["test/controllers/#{m[1]}_test.rb",
-         "test/functional/#{m[1]}_test.rb"]
-      end
+      [
+        "test/controllers/#{m[1]}_test.rb",
+        "test/functional/#{m[1]}_test.rb"
+      ]
     end
 
     add_mapping %r%^app/views/layouts/% do
       "test/views/layouts_view_test.rb"
     end
 
-    add_mapping %r%^config/routes.rb$% do # FIX:
-      files_matching %r%^test/(controllers|views|functional)/.*_test\.rb$%
+    # routes -> views + controllers + integration
+    add_mapping %r%^config/routes.rb$% do
+      files_matching %r%^test/(controllers|views|functional|integration)/.*_test\.rb$%
     end
 
+    # config -> everything
     add_mapping %r%^test/test_helper.rb|config/((boot|environment(s/test)?).rb|database.yml)% do
-      files_matching %r%^test/(unit|controllers|views|functional)/.*_test\.rb$%
+      files_matching %r%^test/(#{test_namespaces*'|'})/.*_test\.rb$%
     end
   end
 
-  def ignored_namespaces
-    'unit|functional|integration|views|controllers|helpers|cells'
+  def test_namespaces
+    %w[unit functional integration views controllers helpers cells]
   end
 
   # Convert the pathname s to the name of class.
   def path_to_classname(s)
     sep = File::SEPARATOR
-    parts = s.sub(/^test#{sep}((#{ignored_namespaces})#{sep})?/, '').sub(/\.rb$/, '').split(sep)
+    parts = s.sub(/^test#{sep}((#{test_namespaces*'|'})#{sep})?/, '').sub(/\.rb$/, '').split(sep)
     modules = parts.map { |path| path.split(/_/).map { |seg| seg.capitalize }.join }
     modules[-1] = "#{modules.last}Test" unless modules.last =~ /Test$/
     modules.join('::')
   end
-end
+end
\ No newline at end of file
diff --git a/test/rails_test.rb b/test/rails_test.rb
index c603013..b159c45 100644
--- a/test/rails_test.rb
+++ b/test/rails_test.rb
@@ -27,4 +27,4 @@ class RailsTest < MiniTest::Unit::TestCase
       end
     end
   end
-end
+end
\ No newline at end of file