public function testAssertValidChildClassInstance()
{
$cm = new ClassMetadata('Doctrine\\Tests\\ODM\\PHPCR\\Mapping\\Person');
$cm->initializeReflection(new RuntimeReflectionService());
$childCm = new ClassMetadata('Doctrine\\Tests\\ODM\\PHPCR\\Mapping\\Customer');
$childCm->initializeReflection(new RuntimeReflectionService());
$cm->setChildClasses(array('Doctrine\\Tests\\ODM\\PHPCR\\Mapping\\Person'));
$result = $cm->assertValidChildClass($childCm);
$this->assertNull($result);
}