Run Unit Test?

Multi-Vendor Questions
1
  1. How to run existing unit-test for cs-cart core to check whether the change break the core?
  2. How to structure unit-test for my custom add on and run the unit test? because when i check some add on that preinstalled with the cs-cart there are some have test case and some doesn't have any test case at all and there's no instruction to run the test case

Any help would be very helpful

2
app/lib/vendor/bin/phpunit --bootstrap app/lib/vendor/autoload.php app/addons/produc
t_variations

Fatal error: Class 'Tygh\Tests\Unit\ATestCase' not found in /var/www/html/app/addons/product_variations/tests/Product/Group/GroupTest.php on line 19