function testDataIntegrityWhenTwoSubclassesHaveSameField()
{
// Save data into DataObjectTest_SubTeam.SubclassDatabaseField
$obj = new DataObjectTest_SubTeam();
$obj->SubclassDatabaseField = "obj-SubTeam";
$obj->write();
// Change the class
$obj->ClassName = 'OtherSubclassWithSameField';
$obj->write();
$obj->flushCache();
// Re-fetch from the database and confirm that the data is sourced from
// OtherSubclassWithSameField.SubclassDatabaseField
$obj = DataObject::get_by_id('DataObjectTest_Team', $obj->ID);
$this->assertNull($obj->SubclassDatabaseField);
// Confirm that save the object in the other direction.
$obj->SubclassDatabaseField = 'obj-Other';
$obj->write();
$obj->ClassName = 'DataObjectTest_SubTeam';
$obj->write();
$obj->flushCache();
// If we restore the class, the old value has been lying dormant and will be available again.
// NOTE: This behaviour is volatile; we may change this in the future to clear fields that
// are no longer relevant when changing ClassName
$obj = DataObject::get_by_id('DataObjectTest_Team', $obj->ID);
$this->assertEquals('obj-SubTeam', $obj->SubclassDatabaseField);
}
