node-browser-environment/test/jsdom arg should set jsdom config.js

Simulates a global browser environment using jsdom

import test from 'ava';
import browserEnv from '../dist';

test(t => {
  const userAgent = 'Custom user agent';
  t.is(typeof navigator, 'undefined');
  browserEnv(['navigator'], { userAgent: userAgent });
  t.is(navigator.userAgent, userAgent);
});