(PHP): Testing models with Zend_Test_PHPUnit_DatabaseTestCase

When I run my PHP unit test I get:

1) Test_Model_Mapper_TestTest::testTest
Argument 1 passed to PHPUnit_Extensions_Database_DataSet_DefaultTableIterator::__construct() must be an array, null given, called in /usr/share/php/PHPUnit/Extensions/Database/DataSet/AbstractXmlDataSet.php on line 134 and defined

/var/www/kosheroven/library/Zend/Test/PHPUnit/Db/Operation/Truncate.php:73
/var/www/kosheroven/tests/ModelTestCase.php:79
/var/www/kosheroven/tests/application/models/mappers/TestTest.php:33

Expected result is for the test to pass, obviously. By sprinkling around a few echoes I discovered that this is caused from within the parent::setUp() call, but I have no idea why. I am completely stuck. Any help would be greatly appreciated.

// /tests/ModelTestCase.php

abstract class Test_ModelTestCase extends Zend_Test_PHPUnit_DatabaseTestCase
{
    public $application;
    protected $_db;
    protected $_model;
    protected $_modelClass;
    protected $_filesDir;

    public function setUp()
    {
        $this->application = new Zend_Application(
            APPLICATION_ENV,
            APPLICATION_PATH . '/configs/application.ini'
        );

        $this->bootstrap = array($this, 'appBootstrap');

        $this->_filesDir  = dirname(__FILE__) . '/files/';
        $this->_filesDir .= str_replace('_', '/', get_class($this));
        $this->_model     = new $this->_modelClass();
        // echo '123'; is printed
        parent::setUp();
        // echo '456'; is not
    }

    public function appBootstrap()
    {
        $this->application->bootstrap();
    }

    protected function getConnection()
    {
        if(empty($this->_db))
        {
            $options = $this->application->getOptions();
            $schema = $options['resources']['db']['params']['dbname'];
            $db = $this->application->getBootstrap()->getPluginResource('db')
                    ->getDbAdapter();

            $this->_db = $this->createZendDbConnection($db, $schema);
        }

        return $this->_db;
    }

    protected function getDataSet()
    {
        return $this->createXmlDataSet(dirname(__FILE__) . '/files/seed.xml');
    }
}

// /tests/Model/Mapper/TestTest.php

class Test_Model_Mapper_TestTest extends Test_ModelTestCase
{
    protected $_modelClass = 'Application_Model_Mapper_Ingredients';

    public function testTest()
    {
        $this->assertTrue(true);
    }
}