customer.setProperty("test", "third");
customer.save();
assertEquals("third", customer.getProperty("test"));
customer = new Item(database, "customer0");
assertEquals("third", customer.getProperty("test"));
customer.clearProperty("test");
assertEquals(0, customer.getProperties().size());
customer.save();
customer = new Item(database, "customer0");
assertEquals(0, customer.getProperties().size());
}