title: PHP Fatal error: Class 'WP_UnitTestCase' not found - phpunit
body: <p>I know that it already has answer in <a href="https://stackoverflow.com/questions/56763165/php-fatal-error-class-wp-unittestcase-not-found-when-trying-to-run-test-sampl">PHP Fatal error: Class &#39;WP_UnitTestCase&#39; not found when trying to run test-sample</a> But it doesn't fixed my issue. I am trying to initialize <code>php unit testing</code> with my <code>wordpress plugin</code> using <code>phpunit</code>. I found this tutorial and it was easy to follow. Here's the link 
  <a href="https://www.smashingmagazine.com/2017/12/automated-testing-wordpress-plugins-phpunit/" rel="nofollow noreferrer">https://www.smashingmagazine.com/2017/12/automated-testing-wordpress-plugins-phpunit/</a></p>
  
  <p>Everything was working great until the below step.</p>
  
  <p>When I came to this Step in tutorial where the command  I tried to run</p>
  
  <pre><code>phpunit tests/test-sample.php
  </code></pre>
  
  <p>and I get:</p>
  
  <pre><code>PHP Fatal error:  Class 'WP_UnitTestCase' not found in PHP Fatal error:  Class 'WP_UnitTestCase' not found in /var/www/html/testwordpress/wp-content/plugins/wp-ultimate-csv-importer/tests/test-sample.php on line 11
  </code></pre>
  
  <p>I don't Know how to solve this issue. I found the same question in Stackoverflow. Here's the Link: 
  <a href="https://stackoverflow.com/questions/56763165/php-fatal-error-class-wp-unittestcase-not-found-when-trying-to-run-test-sampl">PHP Fatal error: Class &#39;WP_UnitTestCase&#39; not found when trying to run test-sample</a>
  But it was in  windows. Somehow he managed to fix it. I checked his solution and it says that issue in MySQL. </p>
  
  <p>But in my case, MySQL works fine and  I am in linux with the flavor of Ubuntu. Help me with some solutions to fix this problem in Linux</p>