package random import ( "math/rand" "sync" "testing" ) // for go test -v -race func TestConcurrency(t *testing.T) { rnd := rand.New(NewSource()) var wg sync.WaitGroup for i := 0; i < 10; i++ { wg.Add(1) go func() { rnd.Int63() wg.Done() }() } wg.Wait() }