mockito
Tasty mocking framework for unit tests in Java

https://site.mockito.org/

https://javadoc.io/doc/org.mockito/mockito-core/latest/org/mockito/Mockito.html
https://javadoc.io/doc/org.mockito/mockito-core/1.10.19/org/mockito/Mockito.html



待测的类标注为 @InjectMocks，将其依赖的其他类标注为 @Mock

使用 MockitoAnnotations.initMocks 或 @RunWith(MockitoJUnitRunner.class)
进行mock 注入 

@RunWith(MockitoJUnitRunner.class) 的作用
this runner adds following behavior:
  Initializes mocks annotated with @Mock
  so that explicit usage of   MockitoAnnotations#initMocks(Object) is not necessary. 
  Mocks are initialized before each test method.



public class OrderServiceTest {
	
    @InjectMocks
    OrderServiceImpl orderService;
    @Mock
    private OrderDao orderDao;
    
    @Before
    public void setUp(){
        MockitoAnnotations.initMocks(this);
    }
	

@RunWith(MockitoJUnitRunner.class)
public class OrderServiceTest2 {
	
    @InjectMocks
    OrderServiceImpl orderService;
    @Mock
    private OrderDao orderDao;


Order order = new Order();
Mockito.when(orderDao.getOrderById(Mockito.anyInt())).thenReturn(order);


OrderServiceTest

package dyyx.demo.order;

import org.junit.Before;
import org.junit.Test;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.Mockito;
import org.mockito.MockitoAnnotations;

public class OrderServiceTest {
	
    @InjectMocks
    OrderServiceImpl orderService;
    @Mock
    private OrderDao orderDao;
    
    
    @Before
    public void setUp(){
        // 不使用 @RunWith(MockitoJUnitRunner.class) ，需要显式初始化
        MockitoAnnotations.initMocks(this);
    }
	
	
    @Test
    public void getOrderByIdTest() {
	System.out.println("OrderServiceTest.getOrderByIdTest run");
	Order order = new Order();
	order.setId(9);
        Mockito.when(orderDao.getOrderById(Mockito.anyInt())).thenReturn(order);
        System.out.println(orderService.getOrderById(1));
        System.out.println(orderService.getOrderById(2));
    }
	
    @Test
    public void getOrderByIdTest2() {
	System.out.println("OrderServiceTest.getOrderByIdTest2 run");

	Order order = new Order();
	order.setId(888);
        Mockito.when(orderDao.getOrderById(Mockito.anyInt())).thenReturn(order);
        // orderDao = Mockito.mock(OrderDao.class);
        System.out.println(orderService.getOrderById(1));
        System.out.println(orderService.getOrderById(2));
    }

}



完整代码
https://gitee.com/dyyx/hellocode/tree/master/demo/springboot1.5.4demo/src/test/java/dyyx/demo/order