Executing phpunit test in laravel

When I run phpunit tests in Laravel using the following command,

'/vendor/bin/phpunit', 

the tests are executed and the results are generated. I am also able to do tests on a single file.

'/vendor/bin/phpunit </tests/<filename>'.

However, when I execute the following command it fails:

./vendor/bin/phpunit ./

'Fatal error: Class 'Codeception\Module\OrderHelper' not found in /vendor/codeception/codeception/tests/data/claypit/tests/order/ParsedLoadedTest.php on line 2'.

But I could see that the 'OrderHelper' file still exist.

'/vendor/codeception/codeception/tests/data/claypit/tests/_support/OrderHelper.php'

Can anyone help me in this?

via Chebli Mohamed