go-synctest

func TestAfterFunc(t *testing.T) {
    synctest.Test(t, func(*testing.T) {
        ctx, cancel := context.WithCancel(context.Background())

        called := false
        context.AfterFunc(ctx, func() { called = true })

        synctest.Wait() // Wait until all goroutines are blocked
        if called {
            t.Fatal("AfterFunc was called before cancel")
        }

        cancel()

        synctest.Wait() // Wait again
        if !called {
            t.Fatal("AfterFunc was not called after cancel")
        }
    })
}