singleton improvements

Author: sensorario

antipattern/singleton/singleton.go

@@ -1,14 +1,16 @@
 package singleton
 
 type singleton struct {
-	calls int
+	calls     int
+	creations int
 }
 
 var instance *singleton
 
 func GetInstance() *singleton {
 	if instance == nil {
 		instance = new(singleton)
+		instance.creations = 1
 	}
 	instance.calls++
 	return instance
@@ -17,3 +19,7 @@ func GetInstance() *singleton {
 func (s *singleton) NumberOfCalls() int {
 	return s.calls
 }
+
+func (s *singleton) NumberOfCreations() int {
+	return s.creations
+}

antipattern/singleton/singleton_test.go

@@ -5,6 +5,10 @@ import "testing"
 func TestGetInstance(t *testing.T) {
 	firstInstance := GetInstance()
 
+	if firstInstance.NumberOfCreations() != 1 {
+		t.Error("expected just one number of creations")
+	}
+
 	secondInstance := GetInstance()
 	if firstInstance != secondInstance {
 		t.Error("expected same instance")
@@ -14,4 +18,8 @@ func TestGetInstance(t *testing.T) {
 	if thirdInstance.NumberOfCalls() != 3 {
 		t.Error("expected three calls")
 	}
+
+	if firstInstance.NumberOfCreations() != 1 {
+		t.Error("expected just one number of creations")
+	}
 }