How to write a test to protect against race condition?

Question

go

Let's say I have some library

package v1

var balance int

//Deposit ...
func Deposit(amount int) {
  balance = balance + amount
}

//Balance ...
func Balance() int {
  return balance
}

func setBalance(amount int) {
  balance = amount
}

A race condition is possible here if the function is called in different goroutines.
Does such a test case have the right to life?

func TestRaceDeposit(t *testing.T) {
  setBalance(0)
  ch := make(chan struct{})
  go func() {
    Deposit(10)
    ch <- struct{}{}
  }()
  Deposit(10)
  <-ch
  if Balance() != 20 {
    t.Errorf("unexpected balance: value - %d expect 20", Balance())
  }
}

To be able to catch a race condition when running tests with the -race flag

Answer 1

I would write like this

func TestRaceDeposit(t *testing.T) {
  setBalance(0)

  var wg sync.WaitGroup
  for i := 0; i < 10; i++ {
    wg.Add(1)
    go func() {
      Deposit(10)
      wg.Done()
    }()
  }

  wg.Wait()

  expect := 100
  got := Balance()
  if got != expect {
    t.Errorf("unexpected balance: value - %d expect %d", got, expect)
  }
}