Wait for a function to finish in golang

I have the following code in golang:

func A(){
  go print("hello")
}

func main() {
  A()
  // here I want to wait for the print to happen
  B()
}

How can I somehow ensure that B() will be executed only after the print has happened?

>Solution :

Use sync.Mutex

var l sync.Mutex

func A() {
    go func() {
        print("hello")
        l.Unlock()
    }()
}

func B() {
    print("world")
}

func TestLock(t *testing.T) {
    l.Lock()
    A()
    l.Lock()
    // here I want to wait for the print to happen
    B()
    l.Unlock()
}

Use sync.WaitGroup

var wg sync.WaitGroup

func A() {
    go func() {
        print("hello")
        wg.Done()
    }()
}

func B() {
    print("world")
}

func TestLock(t *testing.T) {
    wg.Add(1)
    A()
    wg.Wait()
    // here I want to wait for the print to happen
    B()
}

Use chan

func A() chan struct{} {
    c := make(chan struct{})
    go func() {
        c <- struct{}{}
        print("hello")
    }()
    return c
}

func B() {
    print("world")
}

func TestLock(t *testing.T) {
    c := A()
    // here I want to wait for the print to happen
    <-c
    B()
}