diff --git a/test.js b/test.js
index 3f82e4e..f60372f 100644
--- a/test.js
+++ b/test.js
@@ -1,60 +1,66 @@
-global.expect = require('chai').expect;
-global.Plugin = require('./');
-describe('Plugin', function() {
-  var plugin;
+/* eslint no-undef: 0 */
+'use strict';
 
-  beforeEach(function() {
+const expect = require('chai').expect;
+const Plugin = require('./');
+
+describe('Plugin', () => {
+  let plugin;
+
+  beforeEach(() => {
     plugin = new Plugin({});
   });
 
-  it('should be an object', function() {
-    expect(plugin).to.be.ok;
-  });
+  it('should be an object', () => expect(plugin).to.be.ok);
 
-  it('should has #optimize method', function() {
+  it('should has #optimize method', () => {
     expect(plugin.optimize).to.be.an.instanceof(Function);
   });
 
-  it('should compile and produce valid result', function(done) {
-    var content = '#first { font-size: 14px; color: #b0b; }';
-    var expected = '#first{font-size:14px;color:#b0b}';
+  it('should compile and produce valid result', done => {
+    const content = '#first { font-size: 14px; color: #b0b; }';
+    const expected = '#first{font-size:14px;color:#b0b}';
 
-    plugin.optimize({data: content, path: ''}).then(data => {
-      expect(data).to.equal(expected);
-      done();
-    }, error => expect(error).not.to.be.ok);
+    plugin.optimize({data: content, path: ''})
+      .then(data => {
+        expect(data).to.equal(expected);
+        done();
+      })
+      .catch(error => expect(error).not.to.be.ok);
   });
 
-  it('should compile and produce a result clean-css options are reflected in', function(done) {
+  it('should compile and produce a result clean-css options are reflected in', done => {
     plugin.options = {
       keepSpecialComments: 0,
-      keepBreaks: true
+      keepBreaks: true,
     };
 
-    var eol = require('os').EOL;
+    const eol = require('os').EOL;
 
-    var content = '/*! comment */\n#first { color: red; }\r\n#second { color: blue; }';
-    var expected = '#first{color:red}' + eol + '#second{color:#00f}';
+    const content = '/*! comment */\n#first { color: red; }\r\n#second { color: blue; }';
+    const expected = `#first{color:red}${eol}#second{color:#00f}`;
 
-    plugin.optimize({data: content, path: ''}).then(data => {
-      expect(data).to.equal(expected);
-      done();
-    }, error => expect(error).not.to.be.ok);
+    plugin.optimize({data: content, path: ''})
+      .then(data => {
+        expect(data).to.equal(expected);
+        done();
+      })
+      .catch(error => expect(error).not.to.be.ok);
   });
 
-  it('should return a non minified css if path is in "ignore" list', function(done) {
+  it('should return a non minified css if path is in "ignore" list', done => {
     plugin.options = {
-      ignored: /ignore-me\.css/
+      ignored: /ignore-me\.css/,
     };
 
-    var content = '#first { font-size: 14px; color: #b0b; }';
-    var expected = content;
+    const content = '#first { font-size: 14px; color: #b0b; }';
+    const expected = content;
 
-    plugin.optimize({data: content, path: "dist/ignore-me.css"}).then(data => {
-      expect(data).to.equal(expected);
-      done();
-    }, error => expect(error).not.to.be.ok);
+    plugin.optimize({data: content, path: 'dist/ignore-me.css'})
+      .then(data => {
+        expect(data).to.equal(expected);
+        done();
+      })
+      .catch(error => expect(error).not.to.be.ok);
   });
-
-
 });