public function testPrePersist()
 {
     $entity = new OrderLineItem();
     $entity->setPrice(Price::create(42, 'USD'));
     $this->assertEquals(42, $entity->getValue());
     $this->assertEquals('USD', $entity->getCurrency());
     $entity->getPrice()->setValue(84);
     $entity->getPrice()->setCurrency('EUR');
     $this->assertEmpty($entity->getProductSku());
     $this->assertEmpty($entity->getProductUnitCode());
     $entity->setProduct((new Product())->setSku('SKU'));
     $entity->setProductUnit((new ProductUnit())->setCode('kg'));
     $entity->preSave();
     $this->assertEquals(84, $entity->getValue());
     $this->assertEquals('EUR', $entity->getCurrency());
     $this->assertEquals('SKU', $entity->getProductSku());
     $this->assertEquals('kg', $entity->getProductUnitCode());
 }