title: Testcafe unable to determine if an element is enabled or disabled
body: <p>I'm using the TestCafe 0.23.3. I'm trying to verify an element if it is enabled or disabled. Here is the HTML node of the element when it is disabled:</p>
  
  <pre><code>&lt;button class="MuiButtonBase-root-415 MuiButtonBase-disabled-416 MuiButton-root-3719 MuiButton-text-3721 MuiButton-textPrimary-3722 MuiButton-flat-3724 MuiButton-flatPrimary-3725 MuiButton-disabled-3739" tabindex="-1" type="button" disabled=""&gt;&lt;span class="MuiButton-label-3720"&gt;Add Person&lt;/span&gt;&lt;/button&gt;
  </code></pre>
  
  <p>Here is the HTML node of the element when it is enabled:</p>
  
  <pre><code>&lt;button class="MuiButtonBase-root-415 MuiButton-root-7365 MuiButton-text-7367 MuiButton-textPrimary-7368 MuiButton-flat-7370 MuiButton-flatPrimary-7371" tabindex="0" type="button"&gt;&lt;span class="MuiButton-label-7366"&gt;Add Person&lt;/span&gt;&lt;span class="MuiTouchRipple-root-778"&gt;&lt;/span&gt;&lt;/button&gt;
  </code></pre>
  
  <p>Here is my TestCafe code to verify the element:</p>
  
  <pre><code>.expect(Selector('button').withText('Add Person').hasAttribute('disabled'))
  .ok();
  </code></pre>
  
  <p>The above TestCafe code passes for both enabled/disabled state of the element which is incorrect as the expected result is to check if the element is disabled. I'm not sure what is the problem here.</p>