Node 6 compatibility

test/async_utils.js

@@ -1,4 +1,14 @@
 
+// Converts a function that takes a Node-style callback (err, result) as its last argument into a
+// function that returns a Promise. This is equivalent to util.promisify, but is reimplemented here
+// because promisify isn't supported in Node 6.
+// Usage: await asyncifyNode(doSomething)(allParamsExceptCallback)
+function promisify(f) {
+  return (...args) =>
+    new Promise((resolve, reject) =>
+      f(...args, (err, result) => err ? reject(err) : resolve(result)));
+}
+
 // Converts a function that takes a single-parameter callback (like most SDK methods) into a Promise.
 // This is different from util.promisify, which uses Node-style callbacks with two parameters.
 // Usage: await asyncify(callback => doSomething(params, callback))
@@ -83,6 +93,7 @@ function AsyncQueue() {
 
 module.exports = {
   asyncify,
+  promisify,
   sleepAsync,
   withCloseable,
   AsyncQueue,

test/file_data_source-test.js

@@ -1,8 +1,7 @@
 const fs = require('fs');
 const tmp = require('tmp');
-const { promisify } = require('util');
 const dataKind = require('../versioned_data_kind');
-const { asyncify, sleepAsync } = require('./async_utils');
+const { asyncify, promisify, sleepAsync } = require('./async_utils');
 const { stubLogger } = require('./stubs');
 
 const LaunchDarkly = require('../index');

test/polling-test.js

@@ -1,8 +1,7 @@
-const { promisify } = require('util');
 const InMemoryFeatureStore = require('../feature_store');
 const PollingProcessor = require('../polling');
 const dataKind = require('../versioned_data_kind');
-const { asyncify, sleepAsync } = require('./async_utils');
+const { asyncify, promisify, sleepAsync } = require('./async_utils');
 const stubs = require('./stubs');
 
 describe('PollingProcessor', () => {

test/requestor-test.js

@@ -1,7 +1,6 @@
-import { promisify } from 'util';
 import Requestor from '../requestor';
 import * as dataKind from '../versioned_data_kind';
-import { withCloseable } from './async_utils';
+import { promisify, withCloseable } from './async_utils';
 import { createServer, respond, respondJson } from './http_server';
 
 describe('Requestor', () => {