title: How can I extract the properties of an interface using TypeScript (preferably with no 3rd party libs)
body: <p>I need to get the properties of an interface to make sure that they match an object that implements it. For unit testing purposes.</p>
  
  <p>So if changes are made to the interface the unit test should break if it isn't updated with the new members.</p>
  
  <p>I've tried using the ts-transformer-keys package but it throws an error about not being a function.</p>
  
  <pre class="lang-js prettyprint-override"><code>   interface Test {
        mem1: boolean,
        mem2: string
     }
  </code></pre>
  
  <p>I would like to do something like this:</p>
  
  <pre><code>   console.log(Object.keys(Test))
  </code></pre>
  
  <p>and expect</p>
  
  <pre><code>   ['mem1', 'mem2'];
  </code></pre>