public class Employee {
    private String name;
    private Double salary;
    /**
     * @return the name
     */
    public String getName() {
        return name;
    }
    /**
     * @param name the name to set
     */
    public void setName(String name) {
        this.name = name;
    }
    /**
     * @return the salary
     */
    public Double getSalary() {
        return salary;
    }
    /**
     * @param salary the salary to set
     */
    public void setSalary(Double salary) {
        this.salary = salary;
    }
}

public interface EmployeeDao {
    public Employee getEmployee(String name);
 
    public boolean updateEmployee(Employee employee);
 
    public static void deleteEmployee(String name) {
        throw new NullPointerException();
    }
 
    public Exception saveEmployee(Employee employee);
}

public class EmployeeServiceImpl {
    private EmployeeDao employeeDao;
 
    public EmployeeServiceImpl() {
 
    }
 
    public EmployeeServiceImpl(EmployeeDao employeeDao) {
        this.employeeDao = employeeDao;
    }
 
    public Employee getEmployee(String name) {
        return employeeDao.getEmployee(name);
    }
 
    public boolean updateEmployee(Employee employee) {
        return employeeDao.updateEmployee(employee);
    }
 
    public boolean deleteEmployee(String name) {
        try {
            EmployeeDao.deleteEmployee(name);
            return true;
        } catch (Exception e) {
            return false;
        }
    }
 
    public boolean saveEmployee(Employee employee) {
        try {
            employeeDao.saveEmployee(employee);
            return true;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }
}

org.powermock.api.mockito.ClassNotPreparedException: 
The class mock.EmployeeDao not prepared for test.
To prepare this class, add class to the '@PrepareForTest' annotation.
In case if you don't use this annotation, add the annotation on class or  method level. 
	at org.powermock.api.mockito.expectation.reporter.MockitoPowerMockReporter.classNotPrepared(MockitoPowerMockReporter.java:32)

@RunWith(PowerMockRunner.class)
@PrepareForTest({ EmployeeDao.class })
public class EmployeeServiceImplTest {
    @Mock
    public EmployeeDao employeeDao;
    @Mock
    EmployeeServiceImpl employeeServiceImpl;
    // @Before注解的方法會在調(diào)用測試方法前執(zhí)行初始化動作
    @Before
    public void initMocks() {
        // 創(chuàng)建模擬對象EmployeeDao的實例
        employeeDao = mock(EmployeeDao.class);
        // 將模擬對象賦給業(yè)務類實例
        employeeServiceImpl = new EmployeeServiceImpl(employeeDao);
    }
    @Test
    public void getEmployeeTest() {
        String name = "scott";
        Employee employee = new Employee();
        employee.setName("scott");
        employee.setSalary(8888.0);
        // 定義當執(zhí)行employeeDao.getEmployee(name)方法時始終返回employee對象，相當于實現(xiàn)了employeeDao的這個方法
        when(employeeDao.getEmployee(name)).thenReturn(employee);
        /*
         * 下面測試我們想要單元測試的employeeServiceImpl.getEmployee(name)方法 我們已經(jīng)屏蔽了該方法對employeeDao.getEmployee(name)的調(diào)用，相當于解除了依賴
         * 這樣我們只需要關心employeeServiceImpl.getEmployee(name)方法的邏輯是否存在問題
         */
        Employee employee2 = employeeServiceImpl.getEmployee(name);
        System.out.println(employee2.getSalary());
    }
    @Test
    public void updateEmployeeTest() {
        Employee employee = new Employee();
        employee.setName("tiger");
        employee.setSalary(99999.0);
        when(employeeDao.updateEmployee(anyObject())).thenReturn(true);
        Employee employee2 = new Employee();
        employee.setName("scott");
        employee.setSalary(99999.0);
        Boolean boolean1 = employeeServiceImpl.updateEmployee(employee2);
        System.out.println(boolean1);
    }
    @Test
    public void deleteEmployeeTest() {
        String name = "haha";
        // 因為這里調(diào)用的是靜態(tài)方法，因此使用PowerMockito.mockStatic(EmployeeDao.class);來模擬靜態(tài)類
        PowerMockito.mockStatic(EmployeeDao.class);
        // 使用doNothing()定義執(zhí)行下面一句語句時什么也不做
        PowerMockito.doNothing().when(EmployeeDao.class);
        // 這一句由于上面的doNothing()即使會拋異常也不會再拋
        EmployeeDao.deleteEmployee(name);
        // 因此employeeServiceImpl.deleteEmployee(name)執(zhí)行時也沒有發(fā)現(xiàn)異常返回true
        EmployeeServiceImpl employeeServiceImpl = new EmployeeServiceImpl();
        Assert.assertTrue(employeeServiceImpl.deleteEmployee(name));
    }
    @Test
    public void throwDeleteExceptionTest() {
        String name = "haha";
        PowerMockito.mockStatic(EmployeeDao.class);
        // doThrow()定義下面一句語句會拋出異常
        PowerMockito.doThrow(new NullPointerException()).when(EmployeeDao.class);
        EmployeeDao.deleteEmployee(name);
        // 因此employeeServiceImpl.deleteEmployee(name)執(zhí)行會返回false
        EmployeeServiceImpl employeeServiceImpl = new EmployeeServiceImpl();
        assertTrue(employeeServiceImpl.deleteEmployee(name));
    }
    @Test
    public void saveEmployeeTest() {
        Employee employee = new Employee();
        employee.setName("scott");
        employee.setSalary(8888.0);
        // 打樁，定義方法返回的值
        when(employeeDao.saveEmployee(employee)).thenReturn(new NullPointerException());
        // 這里doNothing()沒有生效，原因是這里調(diào)用的是實例方法，不是靜態(tài)方法
        PowerMockito.doNothing().when(employeeDao).saveEmployee(employee);
        employeeServiceImpl.saveEmployee(employee);
    }
    @Test
    public void throwSaveEmployeeTest() {
        Employee employee = new Employee();
        employee.setName("scott");
        employee.setSalary(8888.0);
        when(employeeDao.saveEmployee(employee)).thenReturn(new NullPointerException());
        // 這里的doThrow()實際沒有生效，因為這里調(diào)用的是實例方法，不是靜態(tài)方法，因此不存在使下一句語句拋異常的作用
        PowerMockito.doThrow(new NullPointerException()).when(employeeDao).saveEmployee(employee);
        employeeServiceImpl.saveEmployee(employee);
    }
}