Phpunit Test Caching

Question

I am writing phpunit test in phpstorm, symfony2.

When the name of the test file is HomeSliderTest.php, I get the following error:

Fatal error: Class 'Acme\HardcoreBundle\Test\AcmeWebTestCase' not found in Acme/HardcoreBundle/Tests/Functional/HomeSliderTest.php on line 13

But when I change the file name in something else, than everything works correctly.

Does anyone have an idea what might be the problem?

namespace Acme\HardcoreBundle\Tests\Functional;
use Acme\HardcoreBundle\Test\AcmeWebTestCase;
class HomeSliderTest extends AcmeWebTestCase {...

I do not think that the problem is related to the code, because it works when the file name is different, also the test works on other machines.