title: No coverage information was collected, exit without writing coverage information, istanbul coverage
body: <p>Please does anybody know how i can address this issue ? I have my test:coverage defined as follows.</p>
  
  <pre><code>scripts{
   "test:coverage": "babel-node ./node_modules/.bin/istanbul cover ./node_modules/.bin/_mocha ./src/_utils/__tests__/*.js"
  }
  </code></pre>
  
  <p>and when i run </p>
  
  <pre><code>npm run test:coverage
  </code></pre>
  
  <p>My mocha runs fine and everything else ok. But my istanbul coverage returns the message in the title at the end. Moreover , my coverage folder remains empty. After reading through online, i was convinced that i had to add <code>.istanbul.yml</code> file . I then proceed and add it below </p>
  
  <pre><code>verbose: false
  instrumentation:
      root: ./node_modules/.bin/istanbul
      default-excludes: true
      excludes: []
      embed-source: false
      variable: __coverage__
      compact: true
      preserve-comments: false
      complete-copy: false
      save-baseline: false
      baseline-file: ./coverage/coverage-baseline.json
  reporting:
      print: summary
      reports:
          - lcov
      dir: ./coverage
      watermarks:
          statements: [50, 80]
          lines: [50, 80]
          functions: [50, 80]
          branches: [50, 80]
  hooks:
      hook-run-in-context: false
      post-require-hook: null
  </code></pre>
  
  <p>After i run my test:coverage again, the previous istanbul error dispappear. However, The no coverage message in the title still remains and more coverage folder still remains empty. Please where do i go wrong ? Any help would be appreciated.</p>