ES6 refactor of parameter-validator.js (#6079)

let, const, template strings, export default

lib/utils/parameter-validator.js

 'use strict';
 
-var _ = require('lodash');
-var util = require('util');
+const _ = require('lodash');
+const util = require('util');
 
 function validateDeprecation (value, expectation, options) {
   if (!options.deprecated) {
     return;
   }
 
-  var valid = value instanceof options.deprecated || Object.prototype.toString.call(value) === Object.prototype.toString.call(options.deprecated.call());
+  const valid = value instanceof options.deprecated || Object.prototype.toString.call(value) === Object.prototype.toString.call(options.deprecated.call());
 
   if (valid) {
-    var message = util.format('%s should not be of type "%s"', util.inspect(value), options.deprecated.name);
+    const message = `${util.inspect(value)} should not be of type "${options.deprecated.name}"`;
 
     console.log('DEPRECATION WARNING:', options.deprecationWarning || message);
   }
@@ -26,7 +26,7 @@ function validate (value, expectation) {
     return true;
   }
 
-  throw new Error(util.format('The parameter (value: %s) is no %s.', value, expectation.name));
+  throw new Error(`The parameter (value: ${value}) is no ${expectation.name}`);
 }
 
 function check (value, expectation, options) {
@@ -55,3 +55,5 @@ function check (value, expectation, options) {
 }
 
 module.exports = check;
+module.exports.check = check;
+module.exports.default = check;