title: ERROR in error TS2688: Cannot find type definition file for 'jest'
body: <p>I have an angular 6 application and I'm using karma + jasmine to run my tests. but when I run <code>ng test</code> I'm getting the following error:</p>
  
  <blockquote>
    <p>ERROR in error TS2688: Cannot find type definition file for 'jest'.</p>
  </blockquote>
  
  <p>Any one knows how to solve this problem?</p>