public function testIsEven()
 {
     $col = new PropelCollection();
     $this->assertTrue($col->isEven(), 'isEven() returns true on an empty collection');
     $data = array('bar1', 'bar2', 'bar3');
     $col = new PropelCollection();
     $col->setData($data);
     foreach ($col as $key => $value) {
         $this->assertEquals(!(bool) ($key % 2), $col->isEven(), 'isEven() returns true only when the key is even');
     }
 }