TYPO3 Core

When running UnitTests for UpdateExtensionListTask and the extension Scheduler is not loaded will raise an Fatal error:

PHP Fatal error:  Class 'TYPO3\CMS\Scheduler\Task\AbstractTask' not found in typo3/sysext/extensionmanager/Classes/Task/UpdateExtensionListTask.php on line 32
PHP Stack trace:
PHP   1. {main}() typo3/mod.php:0
PHP   2. require() typo3/mod.php:41
PHP   3. Tx_Phpunit_BackEnd_Module->main() typo3conf/phpunit/Classes/BackEnd/index.php:86
PHP   4. Tx_Phpunit_BackEnd_Module->renderRunTests() typo3conf/phpunit/Classes/BackEnd/Module.php:206
PHP   5. Tx_Phpunit_BackEnd_Module->renderRunningTest() typo3conf/phpunit/Classes/BackEnd/Module.php:288
PHP   6. Tx_Phpunit_BackEnd_Module->runTestCase($testSuiteWithAllTestCases = *uninitialized*, $testResult = *uninitialized*) typo3conf/phpunit/Classes/BackEnd/Module.php:591
PHP   7. PHPUnit_Framework_TestCase->run($result = *uninitialized*) typo3conf/phpunit/Classes/BackEnd/Module.php:804
PHP   8. PHPUnit_Framework_TestResult->run($test = *uninitialized*) typo3conf/phpunit/Composer/vendor/phpunit/phpunit/PHPUnit/Framework/TestCase.php:776
PHP   9. TYPO3\CMS\Extbase\Tests\Unit\BaseTestCase->runBare() typo3conf/phpunit/Composer/vendor/phpunit/phpunit/PHPUnit/Framework/TestResult.php:648
PHP  10. PHPUnit_Framework_TestCase->runBare() typo3/sysext/extbase/Tests/Unit/BaseTestCase.php:49
PHP  11. PHPUnit_Framework_TestCase->runTest() typo3conf/phpunit/Composer/vendor/phpunit/phpunit/PHPUnit/Framework/TestCase.php:831
PHP  12. ReflectionMethod->invokeArgs(*uninitialized*, *uninitialized*) typo3conf/phpunit/Composer/vendor/phpunit/phpunit/PHPUnit/Framework/TestCase.php:976
PHP  13. TYPO3\CMS\Extensionmanager\Tests\Unit\Task\UpdateExtensionListTaskTest->executeCallsUpdateExtListOfRepositoryHelper() typo3conf/phpunit/Composer/vendor/phpunit/phpunit/PHPUnit/Framework/TestCase.php:976
PHP  14. TYPO3\CMS\Core\Core\ClassLoader->loadClass($className = *uninitialized*) typo3conf/phpunit/Composer/vendor/phpunit/phpunit/PHPUnit/Framework/TestCase.php:0
PHP  15. require_once() typo3/sysext/core/Classes/Core/ClassLoader.php:178