scala - How to test scalaz IO? -

consider following io:

val io = (for{       userchoice <- getchar     } yield if (userchoice == 'y') putstr("yes") else putstr("no")).flatmap(identity) 

i trying test this:

    val input: inputstream = new bytearrayinputstream(array('n', 'n')) // not sure why need 2 of them...     system.setin(input)     val output = new bytearrayoutputstream()     system.setout(new java.io.printstream(output))     io.unsafeperformio()     system.setin(new fileinputstream(filedescriptor.in))     system.setout(new printstream(new fileoutputstream(filedescriptor.out)))     output.tostring ==== "no" 

i using specs2 within sbt test. first time run test, passes. second time fails console has reached end of input , sbt in weird state , need kill it.

i suppose there might kind of interaction sbt don't understand exactly. there better way test io?

for kind of interactions think worth developing "mini-language" using free monads , have 2 interpreters, 1 testing using id monad , 1 production using io monad.