The stress utility is intended for catching sporadic failures. It runs a given process in parallel in a loop and collects any failures. Usage:
$ stress ./fmt.test -test.run=TestSometing -test.cpu=10
You can also specify a number of parallel processes with -p flag; instruct the utility to not kill hanged processes for gdb attach; or specify the failure output you are looking for (if you want to ignore some other sporadic failures).