Something is missing:
> php -d 'zend_extension=xdebug.so' vendor/bin/phpunit PHP Warning: Failed loading Zend extension 'xdebug.so' (tried: /usr/lib/php/20180731/xdebug.so (/usr/lib/php/20180731/xdebug.so: cannot open shared object file: No such file or directory), /usr/lib/php/20180731/xdebug.so.so (/usr/lib/php/20180731/xdebug.so.so: cannot open shared object file: No such file or directory)) in Unknown on line 0 PHPUnit 8.5.9 by Sebastian Bergmann and contributors. Error: No code coverage driver is available .................................. 34 / 34 (100%) Time: 176 ms, Memory: 10.00 MB OK (34 tests, 52 assertions) > covers-validator CoversValidator 1.3.0 Validation complete. All @covers tags are valid. > coverage-check ./coverage/clover.xml 100 Invalid input file provided Script coverage-check ./coverage/clover.xml 100 handling the test event returned with error code 1