Allow to change API endpoint for bot

bot.go

@@ -25,9 +25,11 @@ type BotAPI struct {
 	Debug  bool   `json:"debug"`
 	Buffer int    `json:"buffer"`
 
-	Self   User         `json:"-"`
-	Client *http.Client `json:"-"`
+	Self            User         `json:"-"`
+	Client          *http.Client `json:"-"`
 	shutdownChannel chan interface{}
+
+	apiEndpoint string
 }
 
 // NewBotAPI creates a new BotAPI instance.
@@ -43,10 +45,12 @@ func NewBotAPI(token string) (*BotAPI, error) {
 // It requires a token, provided by @BotFather on Telegram.
 func NewBotAPIWithClient(token string, client *http.Client) (*BotAPI, error) {
 	bot := &BotAPI{
-		Token:  token,
-		Client: client,
-		Buffer: 100,
+		Token:           token,
+		Client:          client,
+		Buffer:          100,
 		shutdownChannel: make(chan interface{}),
+
+		apiEndpoint: APIEndpoint,
 	}
 
 	self, err := bot.GetMe()
@@ -59,9 +63,13 @@ func NewBotAPIWithClient(token string, client *http.Client) (*BotAPI, error) {
 	return bot, nil
 }
 
+func (b *BotAPI) SetAPIEndpoint(apiEndpoint string) {
+	b.apiEndpoint = apiEndpoint
+}
+
 // MakeRequest makes a request to a specific endpoint with our token.
 func (bot *BotAPI) MakeRequest(endpoint string, params url.Values) (APIResponse, error) {
-	method := fmt.Sprintf(APIEndpoint, bot.Token, endpoint)
+	method := fmt.Sprintf(bot.apiEndpoint, bot.Token, endpoint)
 
 	resp, err := bot.Client.PostForm(method, params)
 	if err != nil {
@@ -186,7 +194,7 @@ func (bot *BotAPI) UploadFile(endpoint string, params map[string]string, fieldna
 		return APIResponse{}, errors.New(ErrBadFileType)
 	}
 
-	method := fmt.Sprintf(APIEndpoint, bot.Token, endpoint)
+	method := fmt.Sprintf(bot.apiEndpoint, bot.Token, endpoint)
 
 	req, err := http.NewRequest("POST", method, nil)
 	if err != nil {
@@ -490,7 +498,7 @@ func (bot *BotAPI) GetUpdatesChan(config UpdateConfig) (UpdatesChannel, error) {
 				return
 			default:
 			}
-			
+
 			updates, err := bot.GetUpdates(config)
 			if err != nil {
 				log.Println(err)