chore: use babel-register and more ES2015 syntax

.babelrc

@@ -3,5 +3,10 @@
     "targets": {
       "node": 4
     }
-  }]]
+  }]],
+  "env": {
+    "test": {
+      "plugins": ["istanbul"]
+    }
+  }
 }

package.json

@@ -8,24 +8,37 @@
   ],
   "license": "MIT",
   "devDependencies": {
-    "ava": "^0.18.1",
-    "babel-cli": "^6.22.2",
+    "ava": "^0.18.2",
+    "babel-cli": "^6.23.0",
+    "babel-plugin-istanbul": "^4.0.0",
     "babel-preset-env": "^1.1.8",
+    "babel-register": "^6.23.0",
     "coveralls": "^2.11.16",
+    "cross-env": "^3.1.4",
     "nyc": "^10.1.2",
     "semistandard": "^9.2.1"
   },
   "scripts": {
     "build": "babel src --out-dir lib",
     "prepublish": "npm test",
     "pretest": "semistandard && npm run build",
-    "test": "nyc ava"
+    "test": "cross-env NODE_ENV=test nyc ava"
+  },
+  "ava": {
+    "require": [
+      "babel-register"
+    ]
   },
   "nyc": {
+    "require": [
+      "babel-register"
+    ],
     "reporter": [
       "text",
       "lcov"
     ],
-    "check-coverage": true
+    "check-coverage": true,
+    "sourceMap": false,
+    "instrument": false
   }
 }

src/index.js

@@ -1,6 +1,4 @@
-'use strict';
-
-module.exports = function argsert (typeConfig, ...args) {
+export default function argsert (typeConfig, ...args) {
   if (typeof typeConfig !== 'string' || (!isRequired(typeConfig) && !isOptional(typeConfig))) {
     args = [typeConfig];
     typeConfig = '';
@@ -41,7 +39,7 @@ module.exports = function argsert (typeConfig, ...args) {
   });
 
   return true;
-};
+}
 
 function getTypes (typeConfig) {
   return typeConfig.split(' ').reduce((result, str, index) => {

src/promise.js

@@ -1,13 +1,11 @@
-'use strict';
+import argsert from './';
 
-const argsert = require('./');
-
-module.exports = function argsertPromise (...args) {
+export default function argsertPromise (...args) {
   return new Promise((resolve, reject) => {
     try {
       return resolve(argsert(...args));
     } catch (err) {
       return reject(err);
     }
   });
-};
+}

test.js

@@ -1,17 +1,12 @@
 import test from 'ava';
-import argsert from './lib/';
-import argsertPromise from './lib/promise';
+import argsert from './src/';
+import argsertPromise from './src/promise';
 
-test('does not throw exception if optional argument is not provided', async t => {
+test('does not throw exception if optional argument is not provided', t => {
   t.true(argsert('[object]'));
-  t.true(await argsertPromise('[object]'));
 });
 
 test('throws exception if wrong type is provided for optional argument', t => {
-  t.throws(
-    () => argsert('[object|number]', 'hello'),
-    /Invalid first argument. Expected object or number or undefined but received string./
-  );
   t.throws(
     argsertPromise('[object|number]', 'hello'),
     /Invalid first argument. Expected object or number or undefined but received string./