common.rb in net-sftp-2.0.5

- old
+ new

@@ -1,6 +1,7 @@
 require 'test/unit'
 require 'mocha'
+require 'stringio'
 
 begin
   require 'net/ssh'
   require 'net/ssh/version'
   raise LoadError, "wrong version" unless Net::SSH::Version::STRING >= '1.99.0'