Mockito框架入门教程（二）

接上一篇，继续学习其它的....

8、找出冗余的互动(即未被验证到的)

@Test(expected = NoInteractionsWanted.class)

public void find_redundant_interaction(){

List list = mock(List.class);

list.add(1);

list.add(2);

verify(list,times(2)).add(anyInt());

//检查是否有未被验证的互动行为，因为add(1)和add(2)都会被上面的anyInt()验证到，所以下面的代码会通过

verifyNoMoreInteractions(list);

List list2 = mock(List.class);

list2.add(1);

list2.add(2);

verify(list2).add(1);

//检查是否有未被验证的互动行为，因为add(2)没有被验证，所以下面的代码会失败抛出异常

verifyNoMoreInteractions(list2);

}

9、使用注解来快速模拟

在上面的测试中我们在每个测试方法里都mock了一个List对象，为了避免重复的mock，使测试类更具有可读性，我们可以使用下面的注解方式来快速模拟对象：

@Mock

private List mockList;

OK，我们再用注解的mock对象试试

@Test

public void shorthand(){

mockList.add(1);

verify(mockList).add(1);

}

运行这个测试类你会发现报错了，mock的对象为NULL，为此我们必须在基类中添加初始化mock的代码

public class MockitoExample2 {

@Mock

private List mockList;

public MockitoExample2(){

MockitoAnnotations.initMocks(this);

}

@Test

public void shorthand(){

mockList.add(1);

verify(mockList).add(1);

}

}

或者使用built-in runner：MockitoJUnitRunner

@RunWith(MockitoJUnitRunner.class)

public class MockitoExample2 {

@Mock

private List mockList;

@Test

public void shorthand(){

mockList.add(1);

verify(mockList).add(1);

}

}

更多的注解还有@Captor,@Spy,@InjectMocks

10、连续调用

@Test(expected = RuntimeException.class)

public void consecutive_calls(){

//模拟连续调用返回期望值，如果分开，则只有最后一个有效

when(mockList.get(0)).thenReturn(0);

when(mockList.get(0)).thenReturn(1);

when(mockList.get(0)).thenReturn(2);

when(mockList.get(1)).thenReturn(0).thenReturn(1).thenThrow(new RuntimeException());

assertEquals(2,mockList.get(0));

assertEquals(2,mockList.get(0));

assertEquals(0,mockList.get(1));

assertEquals(1,mockList.get(1));

//第三次或更多调用都会抛出异常

mockList.get(1);

}

11、使用回调生成期望值

@Test

public void answer_with_callback(){

//使用Answer来生成我们我们期望的返回

when(mockList.get(anyInt())).thenAnswer(new Answer<Object>() {

@Override

public Object answer(InvocationOnMock invocation) throws Throwable {

Object[] args = invocation.getArguments();

return "hello world:"+args[0];

}

});

assertEquals("hello world:0",mockList.get(0));

assertEquals("hello world:999",mockList.get(999));

}

12、监控真实对象

使用spy来监控真实的对象，需要注意的是此时我们需要谨慎的使用when-then语句，而改用do-when语句

@Test(expected = IndexOutOfBoundsException.class)

public void spy_on_real_objects(){

List list = new LinkedList();

List spy = spy(list);

//下面预设的spy.get(0)会报错，因为会调用真实对象的get(0)，所以会抛出越界异常

//when(spy.get(0)).thenReturn(3);

//使用doReturn-when可以避免when-thenReturn调用真实对象api

doReturn(999).when(spy).get(999);

//预设size()期望值

when(spy.size()).thenReturn(100);

//调用真实对象的api

spy.add(1);

spy.add(2);

assertEquals(100,spy.size());

assertEquals(1,spy.get(0));

assertEquals(2,spy.get(1));

verify(spy).add(1);

verify(spy).add(2);

assertEquals(999,spy.get(999));

spy.get(2);

}

13、修改对未预设的调用返回默认期望值

@Test

public void unstubbed_invocations(){

//mock对象使用Answer来对未预设的调用返回默认期望值

List mock = mock(List.class,new Answer() {

@Override

public Object answer(InvocationOnMock invocation) throws Throwable {

return 999;

}

});

//下面的get(1)没有预设，通常情况下会返回NULL，但是使用了Answer改变了默认期望值

assertEquals(999, mock.get(1));

//下面的size()没有预设，通常情况下会返回0，但是使用了Answer改变了默认期望值

assertEquals(999,mock.size());

}

14、捕获参数来进一步断言

@Test

public void capturing_args(){

PersonDao personDao = mock(PersonDao.class);

PersonService personService = new PersonService(personDao);

ArgumentCaptor<Person> argument = ArgumentCaptor.forClass(Person.class);

personService.update(1,"jack");

verify(personDao).update(argument.capture());

assertEquals(1,argument.getValue().getId());

assertEquals("jack",argument.getValue().getName());

}

class Person{

private int id;

private String name;

Person(int id, String name) {

this.id = id;

this.name = name;

}

public int getId() {

return id;

}

public String getName() {

return name;

}

}

interface PersonDao{

public void update(Person person);

}

class PersonService{

private PersonDao personDao;

PersonService(PersonDao personDao) {

this.personDao = personDao;

}

public void update(int id,String name){

personDao.update(new Person(id,name));

}

}

15、真实的部分mock

@Test

public void real_partial_mock(){

//通过spy来调用真实的api

List list = spy(new ArrayList());

assertEquals(0,list.size());

A a  = mock(A.class);

//通过thenCallRealMethod来调用真实的api

when(a.doSomething(anyInt())).thenCallRealMethod();

assertEquals(999,a.doSomething(999));

}

class A{

public int doSomething(int i){

return i;

}

}

16、重置mock

@Test

public void reset_mock(){

List list = mock(List.class);

when(list.size()).thenReturn(10);

list.add(1);

assertEquals(10,list.size());

//重置mock，清除所有的互动和预设

reset(list);

assertEquals(0,list.size());

}