用Mockito　mock在开发环境下无法调用的类或者接口

Posted 2020-06-09

上面的例子是很理想化的状态，但是在实际的开发中，我们需要经常调用一些依赖特定环境的函数或者调用同事写的代码，而同事仅提供了接口。这个时候就需要利用Mockito来协助我们完成测试。

当然，你可以选择easyMock ,jmock等mock工具

在这里直接引用《PowerMock实战手册》中的例子

待测类：

public class EmployeeService {
    private EmployeeDao employeeDao;

    public EmployeeService(EmployeeDao employeeDao) {
        this.employeeDao = employeeDao;
    }
}

待测类调用的方法

public class EmployeeDao {
    public int getTotal() {
        throw new UnsupportedOperationException();
    }
}

其中　getTotal　就是一个利用正常办法无法测试的函数。

测试类：

public class EmployeeServiceTest  {
    @Mock
    private EmployeeDao employeeDao;
    EmployeeService employeeService;


    @BeforeMethod
    public void init(){
         MockitoAnnotations.initMocks(this);
         employeeService = new EmployeeService(employeeDao);
    }
    

    @Test
    public void testGetTotalEmployee() {
        PowerMockito.when(employeeDao.getTotal()).thenReturn(10);
        int total = employeeService.getTotalEmployee();
        assertEquals(10, total);
    }
}

@Mock 是Mockito的标记　与MockitoAnnotations.initMocks(this)　配合使用，等效于

EmployeeDao employeeDao = Mockito.mock(EmployeeDao.class)

如果些对象在测试类反复使用的话，前一种写法能节省很多代码

@BeforeMethod　是testNG标记　，作用是在运行很一个测试方法之前运行此方法

@Test testNG标识，表明此方法是一个测试方法

PowerMockito.when(employeeDao.getTotal()).thenReturn(10);
录制mock的行为，当调用getTotal方法时，返回10
具体请参照：http://site.mockito.org/mockito/docs/current/org/mockito/Mockito.html

下面是运行结果：

[TestNG] Running:
  C:\Users\changzhz\AppData\Local\Temp\testng-eclipse--599967477\testng-customsuite.xml

PASSED: testGetTotalEmployee

===============================================
    Default test
    Tests run: 1, Failures: 0, Skips: 0
===============================================


===============================================
Default suite
Total tests run: 1, Failures: 0, Skips: 0
===============================================

[TestNG] Time taken by [email protected]: 49 ms
[TestNG] Time taken by [email protected]: 8 ms
[TestNG] Time taken by [email protected]: 37 ms
[TestNG] Time taken by [FailedReporter passed=0 failed=0 skipped=0]: 1 ms
[TestNG] Time taken by [email protected]: 3 ms
[TestNG] Time taken by [email protected]: 5 ms