assertThrows() 运行良好，但应该会失败

Question

我是 junit 的新手，我想知道为什么 assertThrows() 在这两种情况下都能正常工作。为什么在 findById(1L) 的情况下会抛出异常？有一个 id 为 1L 的员工，因此断言应该失败。我说的对吗？

员工服务：

public Employee findById(Long id) {
    return employeeRepository.findById(id)
            .orElseThrow( ()-> new NoSuchElementException("not found"));
}

测试方法：

@ExtendWith(MockitoExtension.class)
class EmployeeManagerTest {

@Mock
private EmployeeRepository employeeRepository;

@InjectMocks
private EmployeeManager employeeManager;

@Test
void shouldThrowExceptionWhenEmployeeNotExist() {

Employee employee = new Employee();
employee.setId(1L);

assertThrows(NoSuchElementException.class, ()-> employeeManager.findById(123L) ); // works well

assertThrows(NoSuchElementException.class, ()-> employeeManager.findById(1L) ); // works well, but should fail, because there is an employee with id 1L
    
        }

}

Answer 1

你应该嘲笑你的 EmployeeRepository 并在你的 EmployeeManager 调用存储库上的 findById 时让它 return 你的员工，或者当你 return 什么都不做想测试失败的案例。我创建了两个单独的测试：

@ExtendWith(MockitoExtension.class)
class EmployeeManagerTest {

    @Mock
    private EmployeeRepository employeeRepository;

    @InjectMocks
    private EmployeeManager employeeManager;

    @Test
    void shouldThrowExceptionWhenEmployeeDoesNotExist() {
        // Given
        
        // Make the repo return an empty optional when the id doesn't exit
        when(employeeRepository.findById(any())).thenReturn(Optional.empty());
        
        // Then
        assertThrows(NoSuchElementException.class, ()-> employeeManager.findById(123L) );
    }
    
    @Test
    void shouldReturnEmployeeWhenItExists() {
        // Given
        Employee employee =  new Employee();
        employee.setId(1L);
        
        // Make the repo return an the employee
        when(employeeRepository.findById(1L)).thenReturn(Optional.of(employee));
        
        // When
        Employee returnedEmployee = employeeManager.findById(1L);
        
        // Then
        assertEquals(employee, returnedEmployee);
    }

}

assertThrows() 运行良好，但应该会失败

assertThrows() works well but it should fail

mockito

junit5