All you do by requiring drug testing for welfare recipients is confirm that drug testing for everyone is ok. Don't be so fast to give up your liberty to get revenge on others.
If I have to pass one to get a job, they need to pass one to get the money I pay in. If I have to pass RANDOM testing TO KEEP MY JOB, they need to pass randoms to keep their welfare. No persons not registered as a Legal or Permanant Resident Alien shall recieve any benifits as you have never paid a dime into this system.
Testing should only occur after accidents to determine fault and in cases where drug use is suspected.
Should also be required of anyone wanting to purchase a gun. And required of anyone running for or holding public office.