title: Jest + Enzyme - test for component visibility to the user
body: <p>Currently we use this to test whether a component has ben rendered:</p>
  
  <pre><code>
  const someComponent = component.find('[data-test="some-component"]').at(0);
  expect(someComponent.length).toBe(1);
  </code></pre>
  
  <p>This is fine, but it isn't actually testing that the component is visible to the user - it simply tests that the component exists. How to test that a component both exists and is visible to the user?</p>