title: TypeError: assert.isNotEmpty is not a function with chai assert
body: <p>I'm getting assert.isNotEmpty is not a function in mocha test when asserting with chai. I have <code>"chai": "^4.1.2"</code> defined in package.json</p>
  
  <pre><code>const assert = require('chai').assert;
  
  assert.isNotEmpty({"foo" : "bar"});
  </code></pre>
  
  <p>results in:</p>
  
  <pre><code>TypeError: assert.isNotEmpty is not a function
  </code></pre>
  
  <p>What am I not seeing?</p>