public boolean isNotEmpty() {
 List<Order> orders = orderRepository.findAll();
 return orders.size() > 0;
 }

protected Order() {}
public Order(Long id, String buyer, int price, int qty) {
 this.id = id;
 this.buyer = buyer;
 this.price = price;
 this.qty = qty;
}

@Test
@DisplayName("isNotEmpty: -> return true")
public void testIsNotEmptyReturnsTrue() throws InstantiationException, IllegalAccessException, InvocationTargetException {
 Object[] orderConstructorArguments1 = new Object[0];
 Order order1 = ((Order) orderConstructor.newInstance(orderConstructorArguments1));
 entityManager1.persist(order1);
 entityManager1.flush();
 boolean actual = orderService.isNotEmpty();
 assertTrue(actual);
}