title: How to test moment.js with different locales in mocha
body: <p>I would like to test my locale-dependent date calculations with mocha. However, the locale does not seem to be reset in the different <code>describe</code> functions:</p>
  
  <pre><code>var expect = require('chai').expect,
      moment = require('moment');
  
  describe('English locale', function () {
      moment.locale('en');
      it('uses Sunday as start of week', function () {
          // Monday, 5th September 2016
          var d = moment('2016-09-05').weekday(0);
          expect(d.date()).to.equal(4);
      });
  });
  
  describe('German locale', function () {
      moment.locale('de');
      it('uses Monday as start of week', function () {
          // Monday, 5th September 2016
          var d = moment('2016-09-05').weekday(0);
          expect(d.date()).to.equal(5);
      });
  });
  </code></pre>
  
  <p>How can I create a a specific "locale" environment inside my <code>describe</code> blocks?</p>
  
  <p>The <a href="http://momentjs.com/docs/#/i18n/instance-locale/" rel="nofollow">documentation</a> shows only how to format objects in a locale-specific way, I want to <em>create</em> moment objects in a specific locale.</p>