Rakefile in yaks-0.2.0 vs Rakefile in yaks-0.3.0

@@ -7,5 +7,14 @@
 task :push => :gem do
   sh "git tag v#{Yaks::VERSION}"
   sh "git push --tags"
   sh "gem push pkg/yaks-#{Yaks::VERSION}.gem"
 end
+
+require 'mutant'
+task :default => :mutant
+
+task :mutant do
+  pattern = ENV.fetch('PATTERN', 'Yaks*')
+  result  = Mutant::CLI.run(%w[-Ilib -ryaks --use rspec --score 100] + [pattern])
+  fail unless result == Mutant::CLI::EXIT_SUCCESS
+end