Use git to get the list of files and test files.

Rakefile

@@ -22,23 +22,10 @@ spec = Gem::Specification.new do |s|
   s.description = "SimpleConfig is a plugin designed to make application-wide configuration settings (e.g. in a Rails app) easy to set and access in an object-oriented fashion."
   s.has_rdoc = false
   s.authors  = ["Luke Redpath"]
-  s.files    = [
-    "lib/simple_config.rb",
-    "lib/simple_config/controller_mixin.rb",
-    "lib/simple_config/utilities.rb",
-    "lib/tasks/simple_config.rake",
-    "init.rb",
-    "Rakefile",
-    "README.textile",
-    "templates/configuration.rb"
-  ]
-  s.test_files = [
-    "test/controller_mixin_test.rb",
-    "test/network_host_test.rb",
-    "test/simple_config_functional_test.rb",
-    "test/simple_config_test.rb",
-    "test/yaml_parser_test.rb"
-  ]
+
+  s.files             = `git ls-files`.split("\n")
+  s.test_files        = `git ls-files -- {test,spec,features}/*`.split("\n")
+  s.require_paths     = %w( lib )
 end
 
 Gem::PackageTask.new(spec) do |pkg|