spring單元測(cè)試之Mockito
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());
復(fù)制代碼用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());
}
復(fù)制代碼@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
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