1. spring單元測(cè)試之Mockito

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        2021-06-16 12:57

        Mockito 是一個(gè)針對(duì) Java 的單元測(cè)試模擬框架,它與 EasyMock 和 jMock 很相似,都是為了簡(jiǎn)化單元測(cè)試過(guò)程中測(cè)試上下文 ( 或者稱之為測(cè)試驅(qū)動(dòng)函數(shù)以及樁函數(shù) ) 的搭建而開(kāi)發(fā)的工具

        相對(duì)于 EasyMock 和 jMock,Mockito 的優(yōu)點(diǎn)是通過(guò)在執(zhí)行后校驗(yàn)?zāi)男┖瘮?shù)已經(jīng)被調(diào)用,消除了對(duì)期望行為(expectations)的需要。其它的 mocking 庫(kù)需要在執(zhí)行前記錄期望行為(expectations),而這導(dǎo)致了丑陋的初始化代碼。

        SpringBoot 中的 pom.xml 文件需要添加的依賴:

            <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
        </dependency>
        復(fù)制代碼

        進(jìn)入 spring-boot-starter-test-2.1.3.RELEASE.pom 可以看到該依賴中已經(jīng)有單元測(cè)試所需的大部分依賴,如:

        junit mockito hamcrest 若為其他 spring 項(xiàng)目,需要自己添加 Junit 和 mockito 項(xiàng)目。

        常用的 Mockito 方法:

        方法名描述
        Mockito.mock(classToMock)模擬對(duì)象
        Mockito.verify(mock)驗(yàn)證行為是否發(fā)生
        Mockito.when(methodCall).thenReturn(value1).thenReturn(value2)觸發(fā)時(shí)第一次返回value1,第n次都返回value2
        Mockito.doThrow(toBeThrown).when(mock).[method]模擬拋出異常。
        Mockito.mock(classToMock,defaultAnswer)使用默認(rèn)Answer模擬對(duì)象
        Mockito.when(methodCall).thenReturn(value)參數(shù)匹配
        Mockito.doReturn(toBeReturned).when(mock).[method]參數(shù)匹配(直接執(zhí)行不判斷)
        Mockito.when(methodCall).thenAnswer(answer))預(yù)期回調(diào)接口生成期望值
        Mockito.doAnswer(answer).when(methodCall).[method]預(yù)期回調(diào)接口生成期望值(直接執(zhí)行不判斷)
        Mockito.spy(Object)用spy監(jiān)控真實(shí)對(duì)象,設(shè)置真實(shí)對(duì)象行為
        Mockito.doNothing().when(mock).[method]不做任何返回
        Mockito.doCallRealMethod().when(mock).[method] //等價(jià)于Mockito.when(mock.[method]).thenCallRealMethod();調(diào)用真實(shí)的方法
        reset(mock)重置mock

        示例:驗(yàn)證行為是否發(fā)生

        //模擬創(chuàng)建一個(gè)List對(duì)象
        List<Integer> mock = Mockito.mock(List.class);
        //調(diào)用mock對(duì)象的方法
        mock.add(1);
        mock.clear();
        //驗(yàn)證方法是否執(zhí)行
        Mockito.verify(mock).add(1);
        Mockito.verify(mock).clear();
        復(fù)制代碼

        多次觸發(fā)返回不同值

        //mock一個(gè)Iterator類
        Iterator iterator = mock(Iterator.class);
        //預(yù)設(shè)當(dāng)iterator調(diào)用next()時(shí)第一次返回hello,第n次都返回world
        Mockito.when(iterator.next()).thenReturn("hello").thenReturn("world");
        //使用mock的對(duì)象
        String result = iterator.next() + " " + iterator.next() + " " + iterator.next();
        //驗(yàn)證結(jié)果
        Assert.assertEquals("hello world world",result);
        復(fù)制代碼

        模擬拋出異常

        @Test(expected = IOException.class)//期望報(bào)IO異常
        public void when_thenThrow() throws IOException{
        OutputStream mock = Mockito.mock(OutputStream.class);
        //預(yù)設(shè)當(dāng)流關(guān)閉時(shí)拋出異常
        Mockito.doThrow(new IOException()).when(mock).close();
        mock.close();
        }
        復(fù)制代碼

        使用默認(rèn)Answer模擬對(duì)象 RETURNS_DEEP_STUBS 是創(chuàng)建mock對(duì)象時(shí)的備選參數(shù)之一 以下方法deepstubsTest和deepstubsTest2是等價(jià)的

          @Test
        public void deepstubsTest(){
        A a=Mockito.mock(A.class,Mockito.RETURNS_DEEP_STUBS);
        Mockito.when(a.getB().getName()).thenReturn("Beijing");
        Assert.assertEquals("Beijing",a.getB().getName());
        }

        @Test
        public void deepstubsTest2(){
        A a=Mockito.mock(A.class);
        B b=Mockito.mock(B.class);
        Mockito.when(a.getB()).thenReturn(b);
        Mockito.when(b.getName()).thenReturn("Beijing");
        Assert.assertEquals("Beijing",a.getB().getName());
        }
        class A{
        private B b;
        public B getB(){
        return b;
        }
        public void setB(B b){
        this.b=b;
        }
        }
        class B{
        private String name;
        public String getName(){
        return name;
        }
        public void setName(String name){
        this.name = name;
        }
        public String getSex(Integer sex){
        if(sex==1){
        return "man";
        }else{
        return "woman";
        }
        }
        }
        復(fù)制代碼

        參數(shù)匹配

        @Test
        public void with_arguments(){
        B b = Mockito.mock(B.class);
        //預(yù)設(shè)根據(jù)不同的參數(shù)返回不同的結(jié)果
        Mockito.when(b.getSex(1)).thenReturn("男");
        Mockito.when(b.getSex(2)).thenReturn("女");
        Assert.assertEquals("男", b.getSex(1));
        Assert.assertEquals("女", b.getSex(2));
        //對(duì)于沒(méi)有預(yù)設(shè)的情況會(huì)返回默認(rèn)值
        Assert.assertEquals(null, b.getSex(0));
        }
        class B{
        private String name;
        public String getName(){
        return name;
        }
        public void setName(String name){
        this.name = name;
        }
        public String getSex(Integer sex){
        if(sex==1){
        return "man";
        }else{
        return "woman";
        }
        }
        }
        復(fù)制代碼

        匹配任意參數(shù) Mockito.anyInt() 任何 int 值 ;Mockito.anyLong() 任何 long 值 ;Mockito.anyString() 任何 String 值 ;

        Mockito.any(XXX.class) 任何 XXX 類型的值 等等。

        @Test
        public void with_unspecified_arguments(){
        List list = Mockito.mock(List.class);
        //匹配任意參數(shù)
        Mockito.when(list.get(Mockito.anyInt())).thenReturn(1);
        Mockito.when(list.contains(Mockito.argThat(new IsValid()))).thenReturn(true);
        Assert.assertEquals(1,list.get(1));
        Assert.assertEquals(1,list.get(999));
        Assert.assertTrue(list.contains(1));
        Assert.assertTrue(!list.contains(3));
        }
        class IsValid extends ArgumentMatcher<List>{
        @Override
        public boolean matches(Object obj) {
        return obj.equals(1) || obj.equals(2);
        }
        }
        復(fù)制代碼

        注意:使用了參數(shù)匹配,那么所有的參數(shù)都必須通過(guò)matchers來(lái)匹配 Mockito繼承Matchers,anyInt()等均為Matchers方法 當(dāng)傳入兩個(gè)參數(shù),其中一個(gè)參數(shù)采用任意參數(shù)時(shí),指定參數(shù)需要matchers來(lái)對(duì)比

        Comparator comparator = mock(Comparator.class);
        comparator.compare("nihao","hello");
        //如果你使用了參數(shù)匹配,那么所有的參數(shù)都必須通過(guò)matchers來(lái)匹配
        Mockito.verify(comparator).compare(Mockito.anyString(),Mockito.eq("hello"));
        //下面的為無(wú)效的參數(shù)匹配使用
        //verify(comparator).compare(anyString(),"hello");
        復(fù)制代碼

        自定義參數(shù)匹配

        @Test
        public void argumentMatchersTest(){
        //創(chuàng)建mock對(duì)象
        List<String> mock = mock(List.class);
        //argThat(Matches<T> matcher)方法用來(lái)應(yīng)用自定義的規(guī)則,可以傳入任何實(shí)現(xiàn)Matcher接口的實(shí)現(xiàn)類。
        Mockito.when(mock.addAll(Mockito.argThat(new IsListofTwoElements()))).thenReturn(true);
        Assert.assertTrue(mock.addAll(Arrays.asList("one","two","three")));
        }

        class IsListofTwoElements extends ArgumentMatcher<List>
        {
        public boolean matches(Object list)
        {
        return((List)list).size()==3;
        }
        }
        復(fù)制代碼

        預(yù)期回調(diào)接口生成期望值

        @Test
        public void answerTest(){
        List mockList = Mockito.mock(List.class);
        //使用方法預(yù)期回調(diào)接口生成期望值(Answer結(jié)構(gòu))
        Mockito.when(mockList.get(Mockito.anyInt())).thenAnswer(new CustomAnswer());
        Assert.assertEquals("hello world:0",mockList.get(0));
        Assert.assertEquals("hello world:999",mockList.get(999));
        }
        private class CustomAnswer implements Answer<String> {
        @Override
        public String answer(InvocationOnMock invocation) throws Throwable {
        Object[] args = invocation.getArguments();
        return "hello world:"+args[0];
        }
        }
        等價(jià)于:(也可使用匿名內(nèi)部類實(shí)現(xiàn))
        @Test
        public void answer_with_callback(){
        //使用Answer來(lái)生成我們我們期望的返回
        Mockito.when(mockList.get(Mockito.anyInt())).thenAnswer(new Answer<Object>() {
        @Override
        public Object answer(InvocationOnMock invocation) throws Throwable {
        Object[] args = invocation.getArguments();
        return "hello world:"+args[0];
        }
        });
        Assert.assertEquals("hello world:0",mockList.get(0));
        Assert. assertEquals("hello world:999",mockList.get(999));
        }
        復(fù)制代碼

        預(yù)期回調(diào)接口生成期望值(直接執(zhí)行)

        @Test
        public void testAnswer1(){
        List<String> mock = Mockito.mock(List.class);
        Mockito.doAnswer(new CustomAnswer()).when(mock).get(Mockito.anyInt());
        Assert.assertEquals("大于三", mock.get(4));
        Assert.assertEquals("小于三", mock.get(2));
        }
        public class CustomAnswer implements Answer<String> {
        public String answer(InvocationOnMock invocation) throws Throwable {
        Object[] args = invocation.getArguments();
        Integer num = (Integer)args[0];
        if( num>3 ){
        return "大于三";
        } else {
        return "小于三";
        }
        }
        }
        復(fù)制代碼

        修改對(duì)未預(yù)設(shè)的調(diào)用返回默認(rèn)期望(指定返回值)

        //mock對(duì)象使用Answer來(lái)對(duì)未預(yù)設(shè)的調(diào)用返回默認(rèn)期望值
        List mock = Mockito.mock(List.class,new Answer() {
        @Override
        public Object answer(InvocationOnMock invocation) throws Throwable {
        return 999;
        }
        });
        //下面的get(1)沒(méi)有預(yù)設(shè),通常情況下會(huì)返回NULL,但是使用了Answer改變了默認(rèn)期望值
        Assert.assertEquals(999, mock.get(1));
        //下面的size()沒(méi)有預(yù)設(shè),通常情況下會(huì)返回0,但是使用了Answer改變了默認(rèn)期望值
        Assert.assertEquals(999,mock.size());
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        用spy監(jiān)控真實(shí)對(duì)象,設(shè)置真實(shí)對(duì)象行為

            @Test(expected = IndexOutOfBoundsException.class)
        public void spy_on_real_objects(){
        List list = new LinkedList();
        List spy = Mockito.spy(list);
        //下面預(yù)設(shè)的spy.get(0)會(huì)報(bào)錯(cuò),因?yàn)闀?huì)調(diào)用真實(shí)對(duì)象的get(0),所以會(huì)拋出越界異常
        //Mockito.when(spy.get(0)).thenReturn(3);

        //使用doReturn-when可以避免when-thenReturn調(diào)用真實(shí)對(duì)象api
        Mockito.doReturn(999).when(spy).get(999);
        //預(yù)設(shè)size()期望值
        Mockito.when(spy.size()).thenReturn(100);
        //調(diào)用真實(shí)對(duì)象的api
        spy.add(1);
        spy.add(2);
        Assert.assertEquals(100,spy.size());
        Assert.assertEquals(1,spy.get(0));
        Assert.assertEquals(2,spy.get(1));
        Assert.assertEquals(999,spy.get(999));
        }
        復(fù)制代碼

        不做任何返回

        @Test
        public void Test() {
        A a = Mockito.mock(A.class);
        //void 方法才能調(diào)用doNothing()
        Mockito.doNothing().when(a).setName(Mockito.anyString());
        a.setName("bb");
        Assert.assertEquals("bb",a.getName());
        }
        class A {
        private String name;
        private void setName(String name){
        this.name = name;
        }
        private String getName(){
        return name;
        }
        }
        復(fù)制代碼

        調(diào)用真實(shí)的方法

        @Test
        public void Test() {
        A a = Mockito.mock(A.class);
        //void 方法才能調(diào)用doNothing()
        Mockito.when(a.getName()).thenReturn("bb");
        Assert.assertEquals("bb",a.getName());
        //等價(jià)于Mockito.when(a.getName()).thenCallRealMethod();
        Mockito.doCallRealMethod().when(a).getName();
        Assert.assertEquals("zhangsan",a.getName());
        }
        class A {
        public String getName(){
        return "zhangsan";
        }
        }
        復(fù)制代碼

        重置 mock

            @Test
        public void reset_mock(){
        List list = mock(List.class);
        Mockito. when(list.size()).thenReturn(10);
        list.add(1);
        Assert.assertEquals(10,list.size());
        //重置mock,清除所有的互動(dòng)和預(yù)設(shè)
        Mockito.reset(list);
        Assert.assertEquals(0,list.size());
        }
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        @Mock 注解

        public class MockitoTest {
        @Mock
        private List mockList;
        //必須在基類中添加初始化mock的代碼,否則報(bào)錯(cuò)mock的對(duì)象為NULL
        public MockitoTest(){
        MockitoAnnotations.initMocks(this);
        }
        @Test
        public void AnnoTest() {
        mockList.add(1);
        Mockito.verify(mockList).add(1);
        }
        }
        復(fù)制代碼

        使用 @MockBean 可以解決單元測(cè)試中的一些依賴問(wèn)題,示例如下:

        @RunWith(SpringRunner.class)
        @SpringBootTest
        public class ServiceWithMockBeanTest {
        @MockBean
        SampleDependencyA dependencyA;
        @Autowired
        SampleService sampleService;

        @Test
        public void testDependency() {
        when(dependencyA.getExternalValue(anyString())).thenReturn("mock val: A");
        assertEquals("mock val: A", sampleService.foo());
        }
        }
        復(fù)制代碼

        @MockBean 只能 mock 本地的代碼——或者說(shuō)是自己寫(xiě)的代碼,對(duì)于儲(chǔ)存在庫(kù)中而且又是以 Bean 的形式裝配到代碼中的類無(wú)能為力。

        @SpyBean 解決了 SpringBoot 的單元測(cè)試中 @MockBean 不能 mock 庫(kù)中自動(dòng)裝配的 Bean 的局限(目前還沒(méi)需求,有需要的自己查閱資料)。


        作者:蔣老濕
        鏈接:https://juejin.cn/post/6973679299500965896
        來(lái)源:掘金
        著作權(quán)歸作者所有。商業(yè)轉(zhuǎn)載請(qǐng)聯(lián)系作者獲得授權(quán),非商業(yè)轉(zhuǎn)載請(qǐng)注明出處。



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