Ignore tests in dummy app

Rakefile

@@ -17,7 +17,7 @@ require 'rake/testtask'
 Rake::TestTask.new(:test) do |t|
   t.libs << 'lib'
   t.libs << 'test'
-  t.pattern = 'test/**/*_test.rb'
+  t.test_files = FileList.new('test/**/*_test.rb').exclude('test/dummy/**/*')
   t.verbose = false
 end