shad-go/once/once_test.go

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2021-03-05 11:27:37 +00:00
package once
import (
"testing"
)
type one int
func (o *one) Increment() {
*o++
}
func run(t *testing.T, once *Once, o *one, c chan bool) {
once.Do(func() { o.Increment() })
if v := *o; v != 1 {
t.Errorf("once failed inside run: %d is not 1", v)
}
c <- true
}
func TestOnce(t *testing.T) {
o := new(one)
once := New()
c := make(chan bool)
const N = 10
for i := 0; i < N; i++ {
go run(t, once, o, c)
}
for i := 0; i < N; i++ {
<-c
}
if *o != 1 {
t.Errorf("once failed outside run: %d is not 1", *o)
}
}
func TestOncePanic(t *testing.T) {
once := New()
func() {
defer func() {
if r := recover(); r == nil {
t.Fatalf("Once.Do did not panic")
}
}()
once.Do(func() {
panic("failed")
})
}()
once.Do(func() {
t.Fatalf("Once.Do called twice")
})
}