singleton.go
// singleton.go
package singleton
type singleton struct {
count int
}
var instance *singleton
func GetInstance() *singleton {
if instance == nil {
instance = new(singleton)
}
return instance
}
func (s *singleton) AddOne() int {
s.count++
return s.count
}
func (s *singleton) GetCount() int {
return s.count
}
singleton_test.go
// singleton_test
package singleton
import (
"testing"
)
func TestGetInstance(t *testing.T) {
counter1 := GetInstance()
if counter1 == nil {
t.Error("A new connectin object must have been made")
}
expectCounter := counter1
currentCount := counter1.AddOne()
if currentCount != 1 {
t.Errorf("After called for the first time, the count value should be 1 but found: %v", currentCount)
}
counter2 := GetInstance()
if counter2 != expectCounter {
t.Error("Singleton instance must not be different")
}
currentCount = counter2.AddOne()
if currentCount != 2 {
t.Errorf("After calling twice of AddOne, currentCount should be 2 but found: %v", currentCount)
}
}
程序输出如下，
image.png
