Require Node.js 6

.travis.yml

@@ -1,7 +1,7 @@
 language: node_js
 node_js:
+  - '10'
   - '8'
   - '6'
-  - '4'
 after_script:
   - './node_modules/.bin/nyc report --reporter=text-lcov | ./node_modules/.bin/coveralls'

index.js

@@ -1,7 +1,7 @@
 'use strict';
 const path = require('path');
 const fsConstants = require('fs').constants;
-const Buffer = require('safe-buffer').Buffer;
+const {Buffer} = require('safe-buffer');
 const CpFileError = require('./cp-file-error');
 const fs = require('./fs');
 const ProgressEmitter = require('./progress-emitter');
@@ -55,8 +55,8 @@ module.exports = (src, dest, opts) => {
 			}
 		});
 
-	promise.on = function () {
-		progressEmitter.on.apply(progressEmitter, arguments);
+	promise.on = (...args) => {
+		progressEmitter.on(...args);
 		return promise;
 	};
 

package.json

@@ -17,7 +17,7 @@
 		}
 	],
 	"engines": {
-		"node": ">=4"
+		"node": ">=6"
 	},
 	"scripts": {
 		"test": "xo && nyc ava"

progress-emitter.js

@@ -20,8 +20,7 @@ class ProgressEmitter extends EventEmitter {
 	}
 
 	emitProgress() {
-		const size = this.size;
-		const written = this.written;
+		const {size, written} = this;
 		this.emit('progress', {
 			src: this.src,
 			dest: this.dest,

test/async.js

@@ -140,7 +140,7 @@ test.serial('rethrow mkdir EACCES errors', async t => {
 });
 
 test.serial('rethrow ENOSPC errors', async t => {
-	const createWriteStream = fs.createWriteStream;
+	const {createWriteStream} = fs;
 	const noSpaceError = buildENOSPC();
 	let called = false;
 

test/helpers/assert.js

@@ -1,6 +1,11 @@
 /**
  * Tests equality of Date objects, w/o considering milliseconds.
  * @see {@link https://github.com/joyent/node/issues/7000|File timestamp resolution is inconsistent with fs.stat / fs.utimes}
+ *
+ * @param {Object} t - AVA's t
+ * @param {*} actual - the actual value
+ * @param {*} expected - the expected value
+ * @param {*} message - error message
  */
 export default function assertDateEqual(t, actual, expected, message) {
 	actual = new Date(actual);