mockito加junit实现单元测试笔记

此文根据视频《mockito加junit搞定单元测试》进行整理，如有侵权，联系删除。

一、简介

1.1 单元测试的特点

• 配合断言使用(杜绝System.out) 。
• 可重复执行 。
• 不依赖环境 。
• 不会对数据产生影响。
• spring的上下文环境不是必须的 。
• 一般都需要配合mock类框架来实现。

1.2 mock类框架使用场景

要进行测试的方法存在外部依赖（如db,redis,第三方接口调用等），为了能够专注于对该方法（单元）的逻辑进行测试，就希望能虚拟出外部依赖，避免外部依赖成为测试的阻塞项。
用到mock类框架进行虚拟这些外部依赖。
一般单元测试都是针对service层。

1.3 常用mock类框架

mock类框架：用于mock外部依赖

1.3.1 mockito

名称：ito：input to output
官网：https://site.mockito.org
官网文档：https://javadoc.io/doc/org.mockito/mockito-core/latest/org/mockito/Mockito.html
限制：老版本对于final class、final method、static method、private method 均不能被 mockito mock。目前已支持final class、final method、static method 的 mock，具体可以参考官网
（39. Mocking final types, enums and final methods (Since 2.1.0)）
（48. New API for mocking static methods (Since 3.4.0)）

原理：bytebuddy 教程：https://www.bilibili.com/video/BV1G24y1a7bd
（通过修改字节码来实现代理的）

1.3.2 easymock

1.3.3 powermock

官网：https://github.com/powermock/powermock
与 mockito 的版本支持关系：https://gitee.com/mirrors/powermock/wikis/Mockito#supported-versions
对 mockito 或 easymock 的增强

1.3.4 JMockit

二、mockito的单独使用

2.1 mock对象与spy对象

	方法插桩	方法不插桩	作用对象	最佳实践
mock对象	执行插桩逻辑	返回mock对象的默认值（0 / null / 空集合）	类、接口	被测试类或其依赖
spy对象	执行插桩逻辑	调用真实方法	类、接口	被测试类

使用 mockingDetails 判断对象是否为 mock对象、spy 对象

2.2 初始化mock/spy对象的方式

	方法一	方法二	方法三
junit4	@RunWith(MockitoJUnitRunner.class) +@Mock等注解	Mockito.mock(X.class)等静态方法	MockitoAnnotations.openMocks(this)+@Mock等注解
junit5	@ExtendWith(MockitoExtension.class) + @Mock等注解	Mockito.mock(X.class)等静态方法	MockitoAnnotations.openMocks(this)+@Mock等注解

初始化mock/spy对象第1种方式

/**
 * 初始化mock/spy对象有3种方式，第1种方式
 */
@RunWith(MockitoJUnitRunner.class)
public class InitMockOrSpyMethod1Test {
    @Mock
    private UserService mockUserService;
    @Spy
    private UserService spyUserService;

    @Test
    public void test1() {
        // true
        System.out.println("Mockito.mockingDetails(mockUserService).isMock() = " + Mockito.mockingDetails(mockUserService).isMock());
        // false
        System.out.println("Mockito.mockingDetails(mockUserService).isSpy() = " + Mockito.mockingDetails(mockUserService).isSpy());
        // true
        System.out.println("Mockito.mockingDetails(spyUserService).isMock() = " + Mockito.mockingDetails(spyUserService).isMock());
        // true
        System.out.println("Mockito.mockingDetails(spyUserService).isSpy() = " + Mockito.mockingDetails(spyUserService).isSpy());
    }
}

初始化mock/spy对象第2种方式

/**
 * 初始化mock/spy对象有3种方式，第2种方式
 */
public class InitMockOrSpyMethod2Test {
    private UserService mockUserService;
    private UserService spyUserService;

    @Before
    public void init() {
        mockUserService = Mockito.mock(UserService.class);
        spyUserService = Mockito.spy(UserService.class);
    }

    @Test
    public void test1() {
        // true
        System.out.println("Mockito.mockingDetails(mockUserService).isMock() = " + Mockito.mockingDetails(mockUserService).isMock());
        // false
        System.out.println("Mockito.mockingDetails(mockUserService).isSpy() = " + Mockito.mockingDetails(mockUserService).isSpy());
        // true
        System.out.println("Mockito.mockingDetails(spyUserService).isMock() = " + Mockito.mockingDetails(spyUserService).isMock());
        // true
        System.out.println("Mockito.mockingDetails(spyUserService).isSpy() = " + Mockito.mockingDetails(spyUserService).isSpy());
    }
}

初始化mock/spy对象第3种方式

/**
 * 初始化mock/spy对象有3种方式，第3种方式
 */
public class InitMockOrSpyMethod3Test {
    @Mock
    private UserService mockUserService;
    @Spy
    private UserService spyUserService;

    @Before
    public void init() {
//        MockitoAnnotations.initMocks(this);
        MockitoAnnotations.openMocks(this);
    }

    @Test
    public void test1() {
        // true
        System.out.println("Mockito.mockingDetails(mockUserService).isMock() = " + Mockito.mockingDetails(mockUserService).isMock());
        // false
        System.out.println("Mockito.mockingDetails(mockUserService).isSpy() = " + Mockito.mockingDetails(mockUserService).isSpy());
        // true
        System.out.println("Mockito.mockingDetails(spyUserService).isMock() = " + Mockito.mockingDetails(spyUserService).isMock());
        // true
        System.out.println("Mockito.mockingDetails(spyUserService).isSpy() = " + Mockito.mockingDetails(spyUserService).isSpy());
    }
}

2.3 参数匹配

/**
 * 参数匹配：通过方法签名（参数）来指定哪些方法调用需要被处理（插桩、verify验证）
 */
@RunWith(MockitoJUnitRunner.class)
public class ParamMatcherTest {
    @Mock
    private UserService mockUserService;

    /**
     * 对于mock对象，不会调用真实方法，直接返回mock对象的默认值
     * 默认值：0（int）、null、空集合
     */
    @Test
    public void test1() {
        UserVO userVO = mockUserService.selectById(1L);
//        userVO = null
        System.out.println("userVO = " + userVO);
        UserUpdateReq userUpdateReq = new UserUpdateReq();
        int i = mockUserService.modifyById(userUpdateReq);
//        i = 0
        System.out.println("i = " + i);
    }

    /**
     * 测试插桩时的参数匹配，只拦截userUpdateReq1
     */
    @Test
    public void test2() {
        UserUpdateReq userUpdateReq1 = new UserUpdateReq();
        userUpdateReq1.setId(1L);
        userUpdateReq1.setPhone("1");
        Mockito.doReturn(99).when(mockUserService).modifyById(userUpdateReq1);

        int result1 = mockUserService.modifyById(userUpdateReq1);
        // result1 = 99
        System.out.println("result1 = " + result1);

        UserUpdateReq userUpdateReq2 = new UserUpdateReq();
        userUpdateReq2.setId(2L);
        userUpdateReq2.setPhone("2");
        int result2 = mockUserService.modifyById(userUpdateReq2);
        // result2 = 0
        System.out.println("result2 = " + result2);

        int result3 = mockUserService.modifyById(userUpdateReq1);
        // result3 = 99
        System.out.println("result3 = " + result3);
    }

    /**
     * 测试插桩时的参数匹配，ArgumentMatchers.any(UserUpdateReq.class)拦截UserUpdateReq类型的任意对象
     * 除了ArgumentMatchers.any(XXX.class)，还有anyXXX()，例如anyString()，anyLong()...
     */
    @Test
    public void test3() {
        Mockito.doReturn(99).when(mockUserService).modifyById(ArgumentMatchers.any(UserUpdateReq.class));

        UserUpdateReq userUpdateReq1 = new UserUpdateReq();
        userUpdateReq1.setId(1L);
        userUpdateReq1.setPhone("1");
        Mockito.doReturn(99).when(mockUserService).modifyById(userUpdateReq1);
        int result1 = mockUserService.modifyById(userUpdateReq1);
        // result1 = 99
        System.out.println("result1 = " + result1);

        UserUpdateReq userUpdateReq2 = new UserUpdateReq();
        userUpdateReq2.setId(2L);
        userUpdateReq2.setPhone("2");
        int result2 = mockUserService.modifyById(userUpdateReq2);
        // result2 = 99
        System.out.println("result2 = " + result2);

        int result3 = mockUserService.modifyById(userUpdateReq1);
        // result3 = 99
        System.out.println("result3 = " + result3);
    }

    /**
     * 测试插桩时的参数匹配，除了ArgumentMatchers.any(XXX.class)，还有anyXXX()，例如anyString()，anyLong()...
     * 注意：anyXXX()不包括null
     */
    @Test
    public void test4() {
        List<String> featureList = new ArrayList<>();
        featureList.add("高");
        featureList.add("富");

        mockUserService.add("zhangsan", "123", featureList);
        mockUserService.add("wangwu", "789", featureList);
//        mockUserService.add("zhangsan", "456", null);

        Mockito.verify(mockUserService, Mockito.times(1)).add("zhangsan", "123", featureList);
        Mockito.verify(mockUserService, Mockito.never()).add("lisi", "123", featureList);
        Mockito.verify(mockUserService, Mockito.times(2)).add(ArgumentMatchers.anyString(), ArgumentMatchers.anyString(), ArgumentMatchers.anyList());
//        不允许部分使用anyXXX表达式
//        Mockito.verify(mockUserService, Mockito.times(2)).add(ArgumentMatchers.anyString(), "123", featureList);
    }
}

2.4 方法插桩

指定调用某个方法时的行为(stubbing)，达到相互隔离的目的

返回指定值

void返回值方法插桩

插桩的两种方式

• when(obj.someMethod()).thenXxx()：其中obj可以是mock对象
• doXxx().when(obj).someMethod()：其中obj可以是mock/spy对象或对无返回值的方法进行插桩

抛异常

多次插桩

thenAnswer

执行真正的原始方法

verify的使用

@RunWith(MockitoJUnitRunner.class)
public class StubTest {
    @Mock
    private List<String> mockList;
    @Mock
    private UserServiceImpl mockUserServiceImpl;
    @Spy
    private UserServiceImpl spyUserServiceImpl;

    /**
     * 指定返回值
     */
    @Test
    public void testReturn() {
        // 方法1
        Mockito.doReturn("zero").when(mockList).get(0);
        Assert.assertEquals("zero", mockList.get(0));

        // 方法2
        Mockito.when(mockList.get(1)).thenReturn("one");
        Assert.assertEquals("one", mockList.get(1));
    }

    /**
     * void返回值方法插桩
     */
    @Test
    public void testVoid() {
        // 调用mockList.clear时候什么都不做
        Mockito.doNothing().when(mockList).clear();
        mockList.clear();
        // 验证调用了一次clear
        Mockito.verify(mockList, Mockito.times(1)).clear();
    }

    /**
     * 插桩的两种方式
     */
    @Test
    public void testReturnMethod() {
        Mockito.when(mockUserServiceImpl.getNumber()).thenReturn(99);
        // 99
        System.out.println("mockUserServiceImpl.getNumber() = " + mockUserServiceImpl.getNumber());

        Mockito.when(spyUserServiceImpl.getNumber()).thenReturn(99);
        // 会打印getNumber
        // 再打印99
        // spy对象在没有插桩时候是调用真实方法的，写在when中会导致先执行一次原方法，达不到mock的目的
        System.out.println("spyUserServiceImpl.getNumber() = " + spyUserServiceImpl.getNumber());

        Mockito.doReturn(999).when(spyUserServiceImpl).getNumber();
        // 99
        System.out.println("spyUserServiceImpl.getNumber() = " + spyUserServiceImpl.getNumber());
    }

    /**
     * 抛出异常
     */
    @Test
    public void testThrowException() {
        // 方法有返回值
        Mockito.when(mockList.get(ArgumentMatchers.anyInt())).thenThrow(RuntimeException.class);
//        Mockito.doThrow(RuntimeException.class).when(mockList).get(ArgumentMatchers.anyInt());
        try {
            mockList.get(4);
            Assert.fail();
        } catch (Exception e) {
            Assert.assertTrue(e instanceof RuntimeException);
        }

        // 方法没返回值
        Mockito.doThrow(RuntimeException.class).when(mockList).clear();
        try {
            mockList.clear();
            Assert.fail();
        } catch (Exception e) {
            Assert.assertTrue(e instanceof RuntimeException);
        }
    }

    /**
     * 多次插桩
     */
    @Test
    public void testMultipleStub() {
        Mockito.when(mockList.size()).thenReturn(1).thenReturn(2).thenReturn(3);
//        Mockito.when(mockList.size()).thenReturn(1, 2, 3);
        Assert.assertEquals(1, mockList.size());
        Assert.assertEquals(2, mockList.size());
        Assert.assertEquals(3, mockList.size());
        Assert.assertEquals(3, mockList.size());
    }

    /**
     * 指定实现逻辑的插桩
     * thenAnswer可以实现对方法进行插桩，以实现自定义返回值逻辑。我们只需实现函数式接口Answer，并实现自定义返回值逻辑即可。
     * 泛型表示要插桩方法的返回值类型，此处我们使用String
     */
    @Test
    public void testThenAnswer() {
        Mockito.when(mockList.get(ArgumentMatchers.anyInt())).thenAnswer(new Answer<String>() {
            @Override
            public String answer(InvocationOnMock invocationOnMock) throws Throwable {
                Integer argument = invocationOnMock.getArgument(0, Integer.class);
                return String.valueOf(argument * 100);
            }
        });
        String result = mockList.get(3);
        Assert.assertEquals("300", result);
    }

    /**
     * 执行真正的原始方法
     */
    @Test
    public void testCallRealMethod() {
        // 对mock对象插桩让它执行原始方法
        Mockito.when(mockUserServiceImpl.getNumber()).thenCallRealMethod();
        int mockResult = mockUserServiceImpl.getNumber();
        Assert.assertEquals(100, mockResult);

        // 不对spy对象插桩，spy对象默认就会调用真实方法
        int spyResult = spyUserServiceImpl.getNumber();
        Assert.assertEquals(100, spyResult);
        // 如果不想spy对象调用真实方法，则需要对它进行插桩
        Mockito.doReturn(999).when(spyUserServiceImpl).getNumber();
        spyResult = spyUserServiceImpl.getNumber();
        Assert.assertEquals(999, spyResult);
    }

    /**
     * 测试verify
     */
    @Test
    public void testVerify() {
        mockList.add("one");
        mockList.add("two");
        mockList.clear();

        Mockito.verify(mockList).add("one");

        Mockito.verify(mockList, Mockito.times(1)).add("one");
        Mockito.verify(mockList, Mockito.times(2)).add(ArgumentMatchers.anyString());

        Mockito.verify(mockList, Mockito.never()).size();
        Mockito.verify(mockList, Mockito.times(0)).size();
    }
}

2.5 @InjectMocks注解的使用

• 作用：若此注解声明的变量需要用到mock/spy对象, mockito会自动使用当前类里的mock或spy成员进行按类型或名字的注入。
• 原理：构造器注入、setter注入、字段反射注入

@RunWith(MockitoJUnitRunner.class)
public class InjectMocksTest {
    // 执行test1方法报错，因为被@InjectMocks注解标注的类必须是实现类，mockito会创建对应的实例对象
//    @InjectMocks
//    private UserService userService;

    // 默认创建的对象就是未经过mockito处理的普通对象
//    @InjectMocks
//    private UserServiceImpl userService;

//    配合@Spy注解使其变成默认调用真实方法的对象
    @InjectMocks
    @Spy
    private UserServiceImpl userService;

//    使用@Mock注解注入到@InjectMocks注解对应的实例对象中
//    如果不使用@Mock注解注入userFeatureService到userService中，执行test1方法过程中，userFeatureService是null
    @Mock
    private UserFeatureService userFeatureService;

    @Test
    public void test1() {
        int number = userService.getNumber();
        Assert.assertEquals(100, number);
    }
}

断言工具

hamcrest：junit4中引入的第三方断言库，junit5中被移出，从1.3版本后，坐标由org.hamcrest:hamcrest-core变为org.hamcrest:hamcrest，用的少
assertj：常用的断言库
junit4原生断言
junit5原生断言

三、实战讲解

四、mockito在springboot环境使用(不推荐)

生成的对象受spring管理
@MockBean

• 类似@Mock
• 用于通过类型或名字替换spring容器中已经存在的bean，从而达到对这些bean进行mock的目的

@SpyBean

• 作用类似@Spy
• 用于通过类型或名字包装spring容器中已经存在的bean，当需要mock被测试类的某些方法时可以使用

附上其他代码

create database mockito_demo CHARACTER SET utf8mb4;
use mockito_demo;
 
drop table if exists user;
CREATE TABLE `user` (
  `id` bigint NOT NULL AUTO_INCREMENT comment '主键',
  `username` varchar(100) NOT NULL comment '用户名称',
  `phone` varchar(50) NOT NULL comment '电话',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB comment '用户表';
 
drop table if exists user_feature;
CREATE TABLE `user_feature` (
  `id` bigint NOT NULL AUTO_INCREMENT comment '主键',
  `user_id` bigint NOT NULL comment '用户id:用户表的主键',
  `feature_value` varchar(150) NOT NULL comment '用户的特征值',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB comment '用户特征表';
 
insert into user(username, phone) values('xiaoming','12345678912');
insert into user_feature(user_id,feature_value) values(1,'abc');
insert into user_feature(user_id,feature_value) values(1,'def');
insert into user_feature(user_id,feature_value) values(1,'ghi');

@SpringBootApplication
@EnableTransactionManagement
@MapperScan("com.lm.mockito.mapper")
public class MockitoApp {
    public static void main(String[] args) {
        SpringApplication.run(MockitoApp.class);
    }
}

@RestController
@Validated
public class UserController {
    @Resource
    private UserService userService;

    @GetMapping("/selectById")
    public UserVO selectById(@NotNull Long userId) {
        return userService.selectById(userId);
    }

    @PostMapping("/add")
    public String add(@RequestBody @Validated UserAddReq addReq) {
        userService.add(addReq.getUserName(), addReq.getPhone(), addReq.getFeatureValueList());
        return "OK";
    }
}

public interface UserService extends IService<UserDO> {
    UserVO selectById(Long userId);

    void add(String userName, String phone, List<String> featureValueList);

    int modifyById(UserUpdateReq userUpdateReq);

    int getNumber();
}

@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, UserDO> implements UserService {
    @Resource
    private UserFeatureService userFeatureService;

    @Override
    public UserVO selectById(Long userId) {
        UserDO existedEntity = getById(userId);
        if (existedEntity == null) {
            return null;
        }

        UserVO userVO = new UserVO();
        BeanUtil.copyProperties(existedEntity, userVO);

        List<UserFeatureDO> featureList = userFeatureService.selectByUserId(userId);
        if (CollectionUtils.isEmpty(featureList)) {
            return userVO;
        }

        userVO.setFeatureValueList(featureList.stream().map(UserFeatureDO::getFeatureValue).collect(Collectors.toList()));
        return userVO;
    }

    @Override
    public void add(String userName, String phone, List<String> featureValueList) {
        UserDO userDO = new UserDO();
        userDO.setUserName(userName);
        userDO.setPhone(phone);
        save(userDO);

        List<UserFeatureDO> userFeatureDOList = featureValueList.stream().map(featureValue -> {
            UserFeatureDO userFeatureDO = new UserFeatureDO();
            userFeatureDO.setUserId(userDO.getId());
            userFeatureDO.setFeatureValue(featureValue);
            return userFeatureDO;
        }).collect(Collectors.toList());
        userFeatureService.saveBatch(userFeatureDOList);
    }

    @Override
    public int modifyById(UserUpdateReq userUpdateReq) {
        UserDO userDO = new UserDO();
        userDO.setId(userUpdateReq.getId());
        userDO.setUserName(userUpdateReq.getUserName());
        userDO.setPhone(userUpdateReq.getPhone());
        boolean successFlag = updateById(userDO);

        return successFlag ? 1 : -1;
    }

    @Override
    public int getNumber() {
        System.out.println("getNumber");
        return 100;
    }
}

public interface UserFeatureService extends IService<UserFeatureDO> {
    List<UserFeatureDO> selectByUserId(Long userId);
}

@Service
public class UserFeatureServiceImpl extends ServiceImpl<UserFeatureMapper, UserFeatureDO> implements UserFeatureService {
    @Override
    public List<UserFeatureDO> selectByUserId(Long userId) {
        if (Objects.isNull(userId)) {
            return null;
        }
        LambdaQueryWrapper<UserFeatureDO> lqw = Wrappers.<UserFeatureDO>lambdaQuery().eq(UserFeatureDO::getUserId,
                userId);
        return list(lqw);
    }
}

public interface UserMapper extends BaseMapper<UserDO> {
}

public interface UserFeatureMapper extends BaseMapper<UserFeatureDO> {
}

@Data
public class UserAddReq {
    @NotBlank
    private String userName;

    @NotBlank
    private String phone;

    @NotEmpty
    private List<String> featureValueList;
}

@Data
public class UserUpdateReq {
    @NotNull
    private Long id;

    @NotBlank
    private String userName;

    @NotBlank
    private String phone;
}

@Data
public class UserVO {
    private Long id;

    private String userName;

    private String phone;

    private List<String> featureValueList;
}

@Data
@TableName("user")
public class UserDO {
    @TableId(type = IdType.AUTO)
    private Long id;

    private String userName;

    private String phone;
}

@Data
@TableName("user_feature")
public class UserFeatureDO {
    @TableId(type = IdType.AUTO)
    private Long id;

    private Long userId;

    private String featureValue;
}

真要mock私有方法，使用powermock