Emit warnings on test

Author: k-tsj

Rakefile

@@ -4,6 +4,6 @@ require "rake/testtask"
 task :default => :test
 Rake::TestTask.new do |t|
   # helper(simplecov) must be required before loading power_assert
-  t.ruby_opts = ["-r./test/helper", "-rpower_assert"]
+  t.ruby_opts = ["-w", "-r./test/helper", "-rpower_assert"]
   t.test_files = FileList["test/test_*.rb"]
 end