feat(support): support Node.js v6.x

- pulls in userland [es6-promisify](https://npm.im/es6-promisify)
- avoids `async` keyword
- add version 6 check to CI
- add `engines` field to `package.json`

index.js

@@ -1,4 +1,4 @@
-const promisify = require('util').promisify
+const {promisify} = require('es6-promisify')
 
 class PromiseModule {
   constructor (mod) {
@@ -13,9 +13,7 @@ const handler = {
     if (target.mod[name]) {
       let val
       if (typeof target.mod[name] === 'function') {
-        val = async (...args) => {
-          return promisify(cb => target.mod[name](...args, cb))()
-        }
+        val = (...args) => promisify(cb => target.mod[name](...args, cb))()
       } else {
         val = target.mod[name]
       }

package.json

@@ -40,5 +40,11 @@
   "repository": {
     "type": "git",
     "url": "https://github.com/boneskull/promwrap.git"
+  },
+  "dependencies": {
+    "es6-promisify": "^6.0.0"
+  },
+  "engines": {
+    "node": ">=6.0.0"
   }
 }

test/test-basics.js

@@ -4,13 +4,15 @@ const promwrap = require('../')
 let fun = (x, cb) => cb(null, x)
 let _module = {fun, prop: 'test'}
 
-test('test basics', async t => {
+test('test basics', t => {
   t.plan(4)
   let mod = promwrap(_module)
   t.same(mod.prop, 'test')
   t.same(mod.prop, 'test')
-  t.same(await mod.fun('test1'), 'test1')
-  t.same(await promwrap(fun)('test2'), 'test2')
+  return Promise.all([
+    mod.fun('test1').then(res => t.same(res, 'test1')),
+    promwrap(fun)('test2').then(res => t.same(res, 'test2'))
+  ])
 })
 
 test('test error', t => {