Add rake dependency for testing.

Author: ioquatix

Gemfile

@@ -1,4 +1,8 @@
 source 'https://rubygems.org'
 
-# Specify your gem's dependencies in rubydns.gemspec
+# Specify your gem's dependencies in trenni.gemspec
 gemspec
+
+group :test do
+gem "rake"
+end