style: use es6 in tests

tests/tap/npm-info.js

@@ -1,13 +1,11 @@
-'use strict'
+const test = require('tap').test
+const nock = require('nock')
 
-var test = require('tap').test
-var nock = require('nock')
+const npmInfo = require('../../dist/lib/npm-info.js')
 
-var npmInfo = require('../../dist/lib/npm-info.js')
+const registry = 'http://registry.npmjs.org/'
 
-var registry = 'http://registry.npmjs.org/'
-
-var defaultModule = {
+const defaultModule = {
   'dist-tags': {
     latest: '1.0.0'
   },
@@ -20,8 +18,8 @@ var defaultModule = {
 
 process.env.npm_config_registry = registry
 
-test('npm-info', function (t) {
-  var regMock = nock(registry, {
+test('npm-info', (t) => {
+  const regMock = nock(registry, {
     reqheaders: {
       'authorization': 'Bearer testtoken'
     }
@@ -31,17 +29,17 @@ test('npm-info', function (t) {
   .get('/@user%2Fmodule')
   .reply(200, defaultModule)
 
-  t.test('get unscoped module', function (t) {
+  t.test('get unscoped module', (t) => {
     t.plan(3)
-    npmInfo('express', function (err, info) {
+    npmInfo('express', (err, info) => {
       t.error(err, 'error')
       t.is(info.version, '1.0.0', 'version')
       t.is(info.gitHead, 'HEAD', 'gitHead')
     })
   })
-  t.test('get scoped module', function (t) {
+  t.test('get scoped module', (t) => {
     t.plan(3)
-    npmInfo('@user/module', function (err, info) {
+    npmInfo('@user/module', (err, info) => {
       t.error(err, 'error')
       t.is(info.version, '1.0.0', 'version')
       t.is(info.gitHead, 'HEAD', 'gitHead')