### Question:
OrderServiceImpl implements OrderService { @Override public void cancelOrder(String orderId, String userId) { OrderProcessContext<String> context = buildContext(orderId, userId,null, ProcessReqEnum.CancelOrder); processEngine.process(context); }  @Override List<OrdersEntity> findOrdersForBuyer(OrderQueryReq orderQueryReq, String buyerId); @Override List<OrdersEntity> findOrdersForSeller(OrderQueryReq orderQueryReq, String sellerId); @Override List<OrdersEntity> findOrdersForAdmin(OrderQueryReq orderQueryReq); @Override String placeOrder(OrderInsertReq orderInsertReq, String buyerId); @Override String pay(String orderId, String userId); @Override void cancelOrder(String orderId, String userId); @Override void confirmDelivery(String orderId, String expressNo, String userId); @Override void confirmReceive(String orderId, String userId);  }### Answer:
@Test public void cancelOrder() throws Exception { orderService.cancelOrder(ORDER_ID, BUYER_ID); }