powermockito单元测试之深刻实践

概述

因为最近工做须要, 在项目中要作单元测试, 以达到指定的测试用例覆盖率指标。项目中咱们引入的powermockito来编写测试用例, JaCoCo来监控单元测试覆盖率。关于框架的选择, 网上讨论mockito和powermockito孰优孰劣的文章众多, 这里就很少作阐述, 读者若有兴趣可自行了解。

依赖引入

<dependency>
    <groupId>org.powermock</groupId>
    <artifactId>powermock-module-junit4-rule-agent</artifactId>
    <version>1.6.6</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.powermock</groupId>
    <artifactId>powermock-api-mockito</artifactId>
    <version>1.6.6</version>
</dependency>
<dependency>
    <groupId>org.powermock</groupId>
    <artifactId>powermock-module-junit4</artifactId>
    <version>1.6.6</version>
</dependency>

被测试类

public class PowerMockitoDemo { @Autowired private StudentDao studentDao; @Autowired private TeacherService teacherService; public void study() { //doSomething
 } private void play(Map<String, Object> project, Person person, int hours) { //doSomething
 } private boolean updateStudentName(String newName) { //doSomething
 } public ServiceResult grantRights(List<String> usernames, String rights, String orderid, String id) { String value1 = PropertiesUtil.get("key1"); String value2 = PropertiesUtil.get("key2"); studentDao.saveRecord(usernames);//返回值类型void
        Student student = studentDao.getStudentById(id); boolean result = this.verifyParams(usernames); teacherService.syncDB2Redis(usernames, orderid); this.updateOperation(rights); } private boolean verifyParams(List<String> usernames) { //doSomething
 } private void updateOperation(String rights) { //doSomething
 } }

测试用例基类

//@PrepareForTest注解和@RunWith注解需结合使用,单独使用将不起做用
@RunWith(PowerMockRunner.class) @PrepareForTest({RedisUtils.class}) @SuppressStaticInitializationFor({"com.test.util.RedisUtils", "com.test.util.HttpUtils"})//用于阻止类中的静态代码块执行
public abstract class BaseTest { public RedisUtils redisUtils; @Rule public ExpectedException thrown = ExpectedException.none();//断言要抛出的异常

    public void setUp() { initMocks(this); PowerMockito.suppress(PowerMockito.constructor(ShardedJedisClientImpl.class, String.class)); redisUtils = PowerMockito.mock(RedisUtils.class); Whitebox.setInternalState(RedisUtils.class, "redisUtil", redisUtils);//给类或实例对象的成员变量设置模拟值,这里是给RedisUtils类中的字段redisUtil设置模拟值
 PowerMockito.suppress(PowerMockito.constructor(HttpUtils.class)); PowerMockito.mockStatic(HttpUtils.class);//mock类中全部静态方法 } /** * @param instance 真实对象 * @param methodName 方法名 * @param args 形参列表 */
    public Object callPrivateMethod(Object instance, String methodName, Object... args) throws Exception { return Whitebox.invokeMethod(instance, methodName, args);//调用私有方法
 } }

测试用例

@PrepareForTest({PowerMockitoDemo.class, PropertiesUtil.class})//此处PowerMockitoDemo被测试类添加到@PrepareForTest注解中, 用于mock其静态、final修饰及私有方法;另外,PropertiesUtil工具类因为不通用,不适合抽取到基类BaseTest中, 可在子类mock
@SuppressStaticInitializationFor("com.test.util.PropertiesUtil")//用于阻止类中的静态代码块执行
public class PowerMockitoDemoTest extends BaseTest{ @org.powermock.core.classloader.annotations.Mock private StudentDao studentDao; @org.powermock.core.classloader.annotations.Mock private TeacherService teacherService; @org.powermock.core.classloader.annotations.Mock @InjectMocks private PowerMockitoDemo powerMockitoDemo; @Override @Before public void setUp() { super.setUp(); PowerMockito.suppress(PowerMockito.constructor(PropertiesUtil.class)); PowerMockito.mockStatic(PropertiesUtil.class);//mock类中全部静态方法
 } @Test public void studyWhenCallSuccessfully() { PowerMockito.doCallRealMethod().when(powerMockitoDemo).study(); //doSomething
 powerMockitoDemo.study(); } @Test public void playWhenCallSuccessfully() { Map<String, Object> project = new HashMap<String, Object>(); Person person = new Person(); int hours = 8; PowerMockito.doCallRealMethod().when(powerMockitoDemo, "play", Matchers.anyMapOf(String.class, Object.class), Matchers.any(Person.class), Matchers.anyInt()); //doSomething

        this.callPrivateMethod(powerMockitoDemo, "play", project, person, hours); } @Test public void updateStudentNameWhenCallSuccessfully() throws Exception { String id = "9527"; PowerMockito.when(powerMockitoDemo, "updateStudentName", Matchers.anyString()).thenCallRealMethod(); //doSomething

        boolean actualResult = this.callPrivateMethod(powerMockitoDemo, "updateStudentName", id); Assert.assertTrue(actualResult == true); } @Test public void getStudentByIdWhenCallSuccessfully() throws Exception { List<String> usernames = new ArrayList<String>(); String rights = "万叶飞花流"; String orderid = "orderid"; String id = "id"; //调用真实方法
        PowerMockito.when(powerMockitoDemo.grantRights(Matchers.anyListOf(String.class), Matchers.anyString(), Matchers.anyString(), Matchers.anyString())).thenCallRealMethod(); //当方法内重复调用同一个方法时, 可经过Matchers.eq()方法来指定实际入参来加以区分
        PowerMockito.when(PropertiesUtil.get(Matchers.eq("key1"))).thenReturn("value1"); PowerMockito.when(PropertiesUtil.get(Matchers.eq("key2"))).thenReturn("value2"); //返回值类型为void,不作任何事情
        PowerMockito.doNothing().when(studentDao).saveRecord(Matchers.anyListOf(String.class)); //相似须要调用数据库、redis、远程服务的,可直接模拟返回值,不作方法的真实调用
        PowerMockito.when(studentDao.getStudentById(Matchers.anyString())).thenReturn(new Student()); //调用真实的私有方法
        PowerMockito.when(powerMockitoDemo, "verifyParams", Matchers.anyListOf(String.class)).thenCallRealMethod(); //模拟私有方法返回值
        PowerMockito.when(powerMockitoDemo, "verifyParams", Matchers.anyListOf(String.class)).thenReturn(true); //模拟方法调用抛出异常。当被调用的方法头没有显式声明异常时, 则mock只支持unchecked exception,好比这里syncDB2Redis()方法签名没有声明任何异常,则thenThrow()模拟异常时只支持模拟运行时异常,使用非运行时异常将编译不经过
        PowerMockito.when(teacherService.syncDB2Redis(Matchers.anyListOf(String.class), Matchers.anyString())).thenThrow(new RuntimeException("Failed to call remote service")); PowerMockito.doNothing().when(powerMockitoDemo, "updateOperation", Matchers.anyString()); ServiceResult expectedResult = new ServiceResult(); ServiceResult actualResult = powerMockitoDemo.grantRights(usernames, rights, orderid, id); //断言实际调用结果是否符合预期值
 Assert.assertEquals(JSON.toJSONString(expectedResult), JSON.toJSONString(actualResult)); } }

如上, 具体的阐释在代码注释中都已经标注, 抽取基类是为了提升代码可重用性。博主这里是为了演示, 因此代码看起来会有点臃肿, 在实际项目使用中, 能够经过静态引入 import static org.mockito.Mockito.when; 和 import static org.mockito.Matchers.*; 来简化代码, 提升可阅读性。

另外因为被测试类在测试方法中被mock掉, 且被@PrepareForTest注解标记时, JaCoCo工具统计测试覆盖率将忽略该测试类。可经过在基类BaseTest中添加 @Rule public ExpectedException thrown = ExpectedException.none(); , 并去掉 @RunWith(PowerMockRunner.class) 和 @SuppressStaticInitializationFor 来使统计测试覆盖率生效。但这里又有一个新问题产生, 基类修改以后, 发现测试用例没法进入debug调试, 所以建议先用修改前的基类来编写单元测试, 便于调试, 待测试用例完成后, 再修改基类令Jacoco统计覆盖率生效。

关于PowerMockito的实践, 博主目前在项目中的使用主要就涉及到了这些, 因此此次作了回标题党"XXX深刻实践" ^_^, 后面若有接触新的相关知识点, 会陆续更新到本篇文章中。若有错误, 欢迎指正, 谢谢你^_^

参考资料

非web下的PowerMockito单元测试