5个编写技巧，有效提高单元测试实践

单元测试（Unit Testing）顾名思义就是测试一个单元，这里的单元通常指一个函数或类，区别于集成测试中的模块和系统。 集成测试的测试过程通常存在跨系统模块的调用，是一种端到端的测试； 而单元测试关注对象的颗粒度较小，用来保障一个类或者函数是否按照预期正确的执行。

3.1.1 单元测试框架JUnit

<dependency>    <groupId>org.springframework.boot</groupId>    <artifactId>spring-boot-starter-test</artifactId>    <scope>test</scope></dependency>

• SpringMVC项目

<dependency>    <groupId>junit</groupId>    <artifactId>junit</artifactId>    <version>4.12</version>    <scope>test</scope></dependency>

<dependency>    <groupId>org.mockito</groupId>    <artifactId>mockito-core</artifactId>    <version>4.7.0</version>    <scope>test</scope></dependency><dependency>    <groupId>org.mockito</groupId>    <artifactId>mockito-inline</artifactId>    <version>4.7.0</version>    <scope>test</scope></dependency>

3.2.2.1 测试方法的命名

@Testpublic void should_returnFalse_when_deleteContent_given_invokeFailed() {    ...}

反例：

@Testpublic void testDeleteContent() {    ...}

@Testpublic void should_returnFalse_when_deleteContent_given_invokeFailed() {    // given    Result<Boolean> deleteDocResult = new Result<>();    deleteDocResult.setEntity(Boolean.FALSE);    when(docManageService.deleteContentDoc(anyLong())).thenReturn(deleteDocResult);    when(docManageService.queryContentDoc(anyLong())).thenReturn(new DocEntity());    // when    Long contentId = 123L;    Boolean result = contentService.deleteContent(contentId);    // then    verify(docManageService, times(1)).queryContentDoc(contentId);    verify(docManageService, times(1)).deleteContentDoc(contentId);    Assert.assertFalse(result);}

@RunWith(MockitoJUnitRunner.class)public class SnsFeedsShareServiceImplTest {    @Mock    SnsFeedsShareHandler snsFeedsShareHandler;    @InjectMocks    SnsFeedsShareServiceImpl snsFeedsShareServiceImpl;    @Test    public void should_returnServiceError_when_shareFeeds_given_invokeFailed() {        // given        Result<Boolean> invokeResult = new Result<>();        invokeResult.setSuccess(Boolean.FALSE);        invokeResult.setModel(Boolean.FALSE);        when(snsFeedsShareHandler.batchShareFeeds(anyLong(), anyString(), anyList())).thenReturn(invokeResult);        // when        Long feedsId = 123L;        String platform = "TEST_SNS_PLATFORM";        List<String> snsAccountList = Collections.singletonList("TEST_SNS_ACCOUNT");        Result<List<String>> result = snsFeedsShareServiceImpl.shareFeeds(feedsId, platform, snsAccountList);        // then        verify(snsFeedsShareHandler, times(1)).batchShareFeeds(feedsId, platform, snsAccountList);        Assert.assertNotNull(result);        Assert.assertEquals(result.getResponseCode(), ResponseEnum.SNS_SHARE_SERVICE_ERROR.getResponseCode());    }}

@RunWith(MockitoJUnitRunner.class)public class ContentServiceTest {    @Mock    DocManageService docManageService;    @InjectMocks    ContentService contentService;    ...}

• MockitoJUnitRunner 使Mockito的注解生效或者使用初始化方法 MockitoAnnotations.initMocks(this)
• 利用 @Mock 模拟各种依赖对象

• 使用 @InjectMocks 将mock出的依赖对象注入到目标测试对象中。以上述代码为例，单测中将 docManageService 注入到 contentService

当然我们也可以使用直接初始化或者 @Spy 的方式来模拟对象，然后使用Setter方法来进行模拟对象的注入，这里介绍了较为简便的方式。

3.4.2.1 Mock无返回值方法

doNothing().when(contentService.deleteContent(anyLong()));

// givenResult<Boolean> deleteResult = new Result<>(Boolean.FALSE);when(contentService.deleteContent(anyLong())).thenReturn(deleteResult);

when(contentService.deleteContent(anyLong())).thenCallRealMethod();

3.4.3.1 验证依赖方法的调用

// 验证调用方法的入参，指定为"testTagId"verify(tagOrmService).queryByValue("testTagId");// 验证queryByValue方法被调用了2次verify(tagOrmService, times(2)).queryByValue(anyString());

MockedStatic<TagHandler> tagHandlerMockedStatic = Mockito.mockStatic(TagHandler.class);tagHandlerMockedStatic.when(() -> TagHandler.getSingleCommonTag(anyString())).thenReturn("tag");

@RunWith(MockitoJUnitRunner.class)public class ContentServiceTest {    @Mock    DocManageService docManageService;    @InjectMocks    ContentService contentService;    private static MockedStatic<TagHandler> tagHandlerMockedStatic = null;    @BeforeClass    public static void beforeTest() {        tagHandlerMockedStatic = Mockito.mockStatic(TagHandler.class);        tagHandlerMockedStatic.when(() -> TagHandler.getSingleCommonTag(anyString())).thenReturn("testTag");    }    // 省略测试方法    @AfterClass    public static void afterTest() {        tagHandlerMockedStatic.close();    }}

2、 在 try-with-resources 构造中定义模拟

@RunWith(MockitoJUnitRunner.class)public class ContentServiceTest {    @Mock    DocManageService docManageService;    @InjectMocks    ContentService contentService;    @Test    public void should_returnEmptyList_when_queryContentTags_given_invokeParams() throws Exception {        try (MockedStatic<TagHandler> tagHandlerMockedStatic = Mockito.mockStatic(TagHandler.class)) {            tagHandlerMockedStatic.when(() -> TagHandler.getSingleCommonTag(anyString())).thenReturn("testTag");            // 省略单测方法具体实现            ...        }    }}

public T select(QueryCondition queryCondition) throws Exception {    LindormQueryParam params = queryCondition.generateQueryParams();    if (Objects.isNull(params)) {        LOGGER.error("Invalid query condition:{}", queryCondition.toString());        return null;    }    Select select = tableService.select()            .from(params.getTableName())            .where(params.getCondition())            .limit(1);    QueryResults results = select.execute();    return convert(results.next());}

@Testpublic void should_returnNull_when_select_given_invalidQueryCondition() throws Exception {    // when    TableService tableService = mock(TableService.class, RETURNS_DEEP_STUBS);    when(tableService.select().from(anyString()).where(any()).limit(anyInt())).thenReturn(null);    Object result = lindormClient.select(new QueryCondition());    // then    Assert.isNull(result);}