public function tearDown($serial)
    {

        // load the registry processor
        $registryProcessor = $this->getRegistryProcessor();

        // update the source directory for the next subject
        $registryProcessor->mergeAttributesRecursive(
            $serial,
            array(
                RegistryKeys::SOURCE_DIRECTORY => $newSourceDir = $this->getNewSourceDir($serial),
                RegistryKeys::FILES => array($this->getFilename() => array(RegistryKeys::STATUS => 1))
            )
        );

        // log a debug message with the new source directory
        $this->getSystemLogger()->debug(
            sprintf('Subject %s successfully updated source directory to %s', get_class($this), $newSourceDir)
        );
    }