implemented factory pattern

creational/factory/factory.go

@@ -0,0 +1,42 @@
+package factory
+
+import (
+	"errors"
+	"fmt"
+)
+
+const (
+	SMS   = 1
+	Email = 2
+)
+
+type Notification struct {
+	To      string
+	Message string
+}
+
+type Notifier interface {
+	SendNotification(Notification) string
+}
+
+type SMSNotification struct{}
+func (n SMSNotification) SendNotification(notification Notification) string {
+	return fmt.Sprintf("`%s` was sent to number `%s` successfully!", notification.Message, notification.To)
+}
+
+type EmailNotification struct{}
+func (n EmailNotification) SendNotification(notification Notification) string {
+	return fmt.Sprintf("`%s` was sent to email `%s` successfully!", notification.Message, notification.To)
+}
+
+// Factory .....
+func GetNotifier(notifierType int) (Notifier, error) {
+	switch notifierType {
+		case SMS:
+			return new(SMSNotification), nil
+		case Email:
+			return new(EmailNotification), nil
+		default:
+		return nil, errors.New(fmt.Sprintf("Notifier type %d not recognized.", notifierType))
+	}
+}

creational/factory/factory_test.go

@@ -0,0 +1,42 @@
+package factory
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestGetSMSNotifier(t *testing.T)  {
+	notification := Notification{"5552233", "Hello world!"}
+	notifier, err := GetNotifier(SMS)
+
+	if err != nil {
+		t.Fatal("Notifier type 'SMS' must be returned")
+	}
+
+	resultStr := notifier.SendNotification(notification)
+	if !strings.Contains(resultStr, "was sent to number") {
+		t.Error("SMS notifier result message was not correct.")
+	}
+}
+
+func TestGetEmailNotifier(t *testing.T)  {
+	notification := Notification{"5552233", "Hello world!"}
+	notifier, err := GetNotifier(Email)
+
+	if err != nil {
+		t.Fatal("Notifier type 'Email' must be returned")
+	}
+
+	resultStr := notifier.SendNotification(notification)
+	if !strings.Contains(resultStr, "was sent to email") {
+		t.Error("Email notifier result message was not correct.")
+	}
+}
+
+func TestGetNonExistanceNotifier(t *testing.T)  {
+	_, err := GetNotifier(3)
+
+	if err == nil {
+		t.Fatal("Error must be returned for unrecognized notifier type.")
+	}
+}