src/telegram: Deprecate auto-enabling Promise cancellation

Side-effects:

  src/telegram: Allow providing custom Promise constructor

References:

  * BR: https://github.com/yagop/node-telegram-bot-api/issues/319

doc/api.md

@@ -12,6 +12,7 @@ TelegramBot
 
 * [TelegramBot](#TelegramBot)
     * [new TelegramBot(token, [options])](#new_TelegramBot_new)
+    * _instance_
         * [.startPolling([options])](#TelegramBot+startPolling) ⇒ <code>Promise</code>
         * ~~[.initPolling([options])](#TelegramBot+initPolling) ⇒ <code>Promise</code>~~
         * [.stopPolling()](#TelegramBot+stopPolling) ⇒ <code>Promise</code>
@@ -74,6 +75,8 @@ TelegramBot
         * [.sendInvoice(chatId, title, description, payload, providerToken, startParameter, currency, prices, [options])](#TelegramBot+sendInvoice) ⇒ <code>Promise</code>
         * [.answerShippingQuery(shippingQueryId, ok, [options])](#TelegramBot+answerShippingQuery) ⇒ <code>Promise</code>
         * [.answerPreCheckoutQuery(preCheckoutQueryId, ok, [options])](#TelegramBot+answerPreCheckoutQuery) ⇒ <code>Promise</code>
+    * _static_
+        * [.Promise](#TelegramBot.Promise)
 
 <a name="new_TelegramBot_new"></a>
 
@@ -974,6 +977,23 @@ Use this method to confirm shipping of a product.
 | ok | <code>Boolean</code> | Specify if every order details are ok |
 | [options] | <code>Object</code> | Additional Telegram query options |
 
+<a name="TelegramBot.Promise"></a>
+
+### TelegramBot.Promise
+Change Promise library used internally, for all existing and new
+instances.
+
+**Kind**: static property of <code>[TelegramBot](#TelegramBot)</code>  
+
+| Param | Type |
+| --- | --- |
+| customPromise | <code>function</code> | 
+
+**Example**  
+```js
+const TelegramBot = require('node-telegram-bot-api');
+TelegramBot.Promise = myPromise;
+```
 * * *
 
 

src/telegram.js

@@ -7,7 +7,6 @@ const TelegramBotPolling = require('./telegramPolling');
 const debug = require('debug')('node-telegram-bot-api');
 const EventEmitter = require('eventemitter3');
 const fileType = require('file-type');
-const Promise = require('bluebird');
 const request = require('request-promise');
 const streamedRequest = require('request');
 const qs = require('querystring');
@@ -18,6 +17,7 @@ const URL = require('url');
 const fs = require('fs');
 const pump = require('pump');
 const deprecate = require('depd')('node-telegram-bot-api');
+let Promise = require('bluebird');
 
 const _messageTypes = [
   'audio',
@@ -49,10 +49,27 @@ const _deprecatedMessageTypes = [
   'new_chat_participant', 'left_chat_participant'
 ];
 
-// enable cancellation
-Promise.config({
+
+// Enable Promise cancellation.
+try {
+  const msg =
+    'Automatic enabling of cancellation of promises is deprecated.\n' +
+    'In the future, you will have to enable it yourself.\n' +
+    'See https://github.com/yagop/node-telegram-bot-api/issues/319.';
+  deprecate(msg);
+  Promise.config({
     cancellation: true,
-});
+  });
+} catch (ex) {
+  /* eslint-disable no-console */
+  const msg =
+    'error: Enabling Promise cancellation failed.\n' +
+    '       Temporary fix is to load/require this library as early as possible before using any Promises.';
+  console.error(msg);
+  throw ex;
+  /* eslint-enable no-console */
+}
+
 
 class TelegramBot extends EventEmitter {
 
@@ -64,6 +81,19 @@ class TelegramBot extends EventEmitter {
     return _messageTypes;
   }
 
+  /**
+   * Change Promise library used internally, for all existing and new
+   * instances.
+   * @param  {Function} customPromise
+   *
+   * @example
+   * const TelegramBot = require('node-telegram-bot-api');
+   * TelegramBot.Promise = myPromise;
+   */
+  static set Promise(customPromise) {
+    Promise = customPromise;
+  }
+
   on(event, listener) {
     if (_deprecatedMessageTypes.indexOf(event) !== -1) {
       const url = 'https://github.com/yagop/node-telegram-bot-api/blob/master/doc/usage.md#events';

test/telegram.js

@@ -109,6 +109,15 @@ describe('TelegramBot', function telegramSuite() {
     });
   });
 
+  it('allows providing custom Promise library', function test() {
+    TelegramBot.Promise = global.Promise;
+    const promise = bot.stopPolling();
+    assert.ok(promise instanceof global.Promise);
+    assert.ok(!(promise instanceof Promise));
+    // revert
+    TelegramBot.Promise = Promise;
+  });
+
   it('automatically starts polling', function test() {
     assert.equal(botPolling.isPolling(), true);
     return utils.isPollingMockServer(pollingPort2);