Inheritance: extends Product_OrderItem
 /**
  * Test {@link OrderItem::__construct()} has set
  * the correct default quantity.
  */
 function testDefaultQuantity()
 {
     $item = new ProductVariation_OrderItem(array());
     $this->assertEquals(1, $item->getField('Quantity'), 'Item quantity is 1 (implicitly set)');
     $item = new ProductVariation_OrderItem(array(), 5);
     $this->assertEquals(5, $item->getField('Quantity'), 'Item quantity is 5');
 }
 function onBeforeWrite()
 {
     parent::onBeforeWrite();
     $this->Quantity = 1;
 }