title: How to enable Test Classes/Called in Assistant Editor of Xcode
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  <p>I want to know how to enable the area with red.</p>
  
  <p>I found this post:
  <a href="https://stackoverflow.com/questions/34340997/use-xcodes-test-classes-assistant-editor-with-swift-classes">Use Xcode&#39;s Test Classes Assistant Editor with Swift Classes</a></p>
  
  <blockquote>
    <p>A file with a base name of FooTest or FooTests is now considered a counterpart of a file with a base name of Foo for navigation and the Assistant Editor. (28981734)</p>
  </blockquote>
  
  <p>I tried, one file named Formula.swift, the other on in Test Projects named FormulaTests.swift, but not worked, do not show in assistant editor auto.</p>
  
  <p>How to enable Test Classes/Called in Assistant Editor of Xcode quickly? Left is source code, right is unit test, that is what I want.</p>