使用JUnit和Mockito模拟内部方法

Question

我有两个方法，jpa类中的第一个方法用于查找id，另一个方法用于创建记录（检查id是否已经存在，如果id不存在，则创建一个记录）。

public class EmployeeRegistry{
public Employee findEmployeeById(String empid){
     List<Employee> results = new ArrayList<Employee>();
     final Query query = entityManager.createNamedQuery("employeeRegistryImpl.findByEmployeeId");
     query.setParameter("empid", empid);
     results = (List<Employee>) query.getResultList();
     if (CollectionUtils.isEmpty(results)) {            
        return null;
     }
     return results.get(0);
}
public Employee createEmployee(final Employee employee) throws PersistenceException{
    if ((findEmployeeById(employee.getId()!=null)) {
        throw new EntityExistsException();
    }
    return entitytManager.merge(employee);
}
}

我用JUnit和Mockito框架为第一个方法findEmployeeById编写了测试用例。例如

@RunWith(MockitoJUnitRunner.class)
public class EmployeeRegistryImplTest{
private String empid = "empid";
@Mock
private static EntityManager entityManager;
@Mock
private static Query query;
@InjectMocks
private static EmployeeRegistry employeeRegistryImpl;
@Test
public void findEmployeeByIdReturnsNull() {
  final List<Employee> employees = new ArrayList<Employee>();
  // given
given(entityManager.createNamedQuery("employeeRegistryImpl.findByEmployeeId")).willReturn(query);
given(query.setParameter("empid", empid)).willReturn(query);
given(query.getResultList()).willReturn(employees);
// when
Employee employeeResult = null;
employeeResult = employeeRegistryImpl.findEmployeeById(empid);
// then
assertNull(employeeResult);
verify(entityManager, Mockito.times(1)).createNamedQuery
("employeeRegistryImpl.findEmployeeById");
}

我试图为createEmployee 编写测试用例

@Test
public void createEmployeeReturnsNotNull() {    
    final Employee employee= new Employee();
    // when
    Employee employee= null;
    employeeResult = employeeRegistryImpl.createEmployee(employee);
    assertNotNull(employeeResult);
}

由于createEmployee方法在内部调用findEmployeeById，并将获得NullPointerException，因此我如何在我的测试类EmployeeRegistryTest中模拟createEmployme方法的findEmployer ById（和empid作为同一方法的输入）。

--在从Mockito文档中检查spy后添加了spy，并获得了empid的NullPointerException。

@Test
public void createEmployeeReturnsNotNull() {
 final Employee employee = new Employee();
 employee.setEmpId(empid);
 final Employee employee2 = new Employee();
 employee2.setEmpId(empid);
 EmployeeRegistryImpl spy = Mockito.spy(employeeRegistryImpl);
    // when
    Employee employeeResult = null;
    try {
        doReturn(employee2).when(spy).findEmployeeById(empid);
        employeeResult = employeeRegistryImpl
                .createUser(employee);
                    // then
        verify(spy).findEmployeeById(empid);
        assertNotNull(employeeResult);
    } catch (Exception e) {
        e.printStackTrace();
    }
}
}
-- Exception after spying
java.lang.NullPointerException
  at EmployeeRegistryImpl.findEmployeeById(EmployeeRegistryImpl.java:)
  at EmployeeRegistryImpl.createEmployee(EmployeeRegistryImpl.java:)
  at EmployeeRegistryImplTest.createEmployeeReturnsNotNull(EmployeeRegistryImplTest.java:)

Answer 1

您可以在testcase中创建新的内部类extendedEmployeeRegistry，并覆盖方法"findEmployeeById"并调用新类的"createEmployee"。

Answer 2

-答案张贴在下方

我了解到我实际上不需要间谍，我也可以模拟内部方法，这很有效：）

例如

@Test
public void createEmployeeThrowsExceptionWhenEmployeeExists() {
 final Employee employee= new Employee();       
 employee.setEmpId(empId);
final List<Employee> employeeList = new ArrayList<Employee>();
employeeList.add(new employee());
// given
given(entityManager.createNamedQuery("employeeRegistryImpl.findByEmployeeId")).willReturn(query);
given(query.setParameter("empId", empId)).willReturn(query);
given(query.getResultList()).willReturn(employeeList);
// when
try {
    employeeRegistryImpl.createUser(employeeList);      
} catch (Exception e) {
// then
    e.getErrorCode());
}
// then
verify(entityManager, Mockito.times(1)).
createNamedQuery("employeeRegistryImpl.findByEmployeeId");
}