PHPUnit Unable to guees the Kernel directory

I'm trying to get a functional test to run, but I get the following error:

PHPUnit 4.5.0 by Sebastian Bergmann and contributors.

E

Time: 47 ms, Memory: 2.00Mb

There was 1 error:

1) Source\Tests\TwitterTest::testActivation
RuntimeException: Unable to guess the Kernel directory.

C:\xampp\htdocs\myfolder\vendor\symfony\symfony\src\Symfony\Bundle\FrameworkBundle\Test\KernelTestCase.php:56
C:\xampp\htdocs\myfolder\vendor\symfony\symfony\src\Symfony\Bundle\FrameworkBundle\Test\KernelTestCase.php:113
C:\xampp\htdocs\myfolder\vendor\symfony\symfony\src\Symfony\Bundle\FrameworkBundle\Test\KernelTestCase.php:159
C:\xampp\htdocs\myfolder\src\Source\Tests\TwitterTest.php:17
C:\xampp\php\pear\PHPUnit\Framework\TestSuite.php:775
C:\xampp\php\pear\PHPUnit\Framework\TestSuite.php:745
C:\xampp\php\pear\PHPUnit\Framework\TestSuite.php:705
C:\xampp\php\pear\PHPUnit\TextUI\TestRunner.php:349
C:\xampp\php\pear\PHPUnit\TextUI\Command.php:176
C:\xampp\php\pear\PHPUnit\TextUI\Command.php:129

FAILURES!
Tests: 1, Assertions: 0, Errors: 1.

I'm his happens when I try to run the following command:

# phpunit src\Source\Tests\

When I try to use the -c option I get the could not read folder error.

Any idea on how can I fix my project to be able to run the tests?