我想为 spring boot 服务方法编写一个 mockito 测试用例

Posted 2023-02-27

【中文标题】我想为 spring boot 服务方法编写一个 mockito 测试用例

【英文标题】：I want to write a mockito test case for a spring boot service method

【发布时间】：2022-01-08 21:03:45

【问题描述】：

这是服务方法。

    @Override
    public void removeStudentByID(Long studentId) throws StudentExistsException 
        boolean exists = studentRepo.existsById(studentId);
        if (!exists) 
            throw new StudentExistsException("Student doesn't exist");
        
        studentRepo.deleteById(studentId);
    

下面是我为它编写的测试用例。

@Test
    public void removeStudentByIdTest() throws StudentExistsException 
        Student student = new Student(1, "Drake", "[e-mail]");
        when(studentRepo.save(student)).thenReturn(student);
        studentService.removeStudentByID(student.getId());
        assertEquals(false, studentRepo.existsById(student.getId()));
    

它没有运行... 但是下面的代码有效。

    public void removeStudent(String email) 
        Student student = studentRepo.findByEmail(email);
        studentRepo.delete(student);
    

@Test
    public void removeStudentTest() throws StudentExistsException 
        Student student = new Student(3, "Ben", "[e-mail]");
        studentRepo.save(student);
        studentService.removeStudent(student.getEmail());
        assertEquals(false, studentRepo.existsById(student.getId()));
    

所以，作为一个菜鸟，我有点困惑如何让它在第一个中起作用。或者他们两个都有问题。

【问题讨论】：

嗨！要测试***方法，您将（正确连接您的模拟，然后）when(studentRepoMock.existsById()).thenReturn(false)（在一个测试中，true 在另一个测试中）...

..当false：断言/预期异常，当true：verify(studentRepoMock.deleteById(1)..

【参考方案1】：

要测试这段代码：

@Service
public class StudentService  
  @Override
  public void removeStudentByID(Long studentId) throws StudentExistsException 
    boolean exists = studentRepo.existsById(studentId);
    if (!exists) 
        throw new StudentExistsException("Student doesn't exist");
    
    studentRepo.deleteById(studentId);
  

我们可以像这样模拟/“单元测试”：

package com.example.demo;

import static org.junit.jupiter.api.Assertions.*;
import static org.mockito.Mockito.*;

import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
class StudenServiceTests  // we only test StudentService, since we (sort of) trust studentRepository (tested it elsewehere/how)

  @Mock // A Mock! (alternatively @MockBean)
  private StudentRepository studentRepoMock;
  @InjectMocks // A real service (with mocks injected;)!!! (alternatively @Autowired/...)
  private StudentService testee; // this guy we want to test (to the bone!)

  @Test // ..the "good case"
  void removeStudentByIdExists() throws StudentExistsException 
    // Given:
    // we don't even need a student, only his id
    // instruct mock for the "first interaction" (see testee code):
    when(studentRepoMock.existsById(1L)).thenReturn(true);
    // instruct mock for "second interaction" (see testee code):
    doNothing().when(studentRepoMock).deleteById(1L); // we could also use ...delete(any(Long.class))  or ..anyLong();

    // When: (do it!)
    testee.removeStudentByID(1L);

    // Then: Verify (interactions, with as exact as possible parameters ..Mockito.any***)
    verify(studentRepoMock).existsById(1L); //.times(n) ...when you had a list ;)
    verify(studentRepoMock).deleteById(1L);
  

  @Test // .. the "bad (but correct) case"/exception
  void removeStudentByIdNotExists() throws StudentExistsException 
    // Given:
    when(studentRepoMock.existsById(1L)).thenReturn(false);

    // When:
    StudentExistsException thrown = assertThrows(
            StudentExistsException.class,
            () -> testee.removeStudentByID(1L),
            "Expected testee.removeStudentByID to throw, but it didn't");
    // Then:
    assertNotNull(thrown);
    assertTrue(thrown.getMessage().contains("Student doesn't exist"));
  

...使用mvn test 运行。

通过这两个测试用例，我们为给定的方法/服务实现了 100% 的测试（和分支）覆盖率。

---

但不要将其与“集成测试”（我们使用真正的 repo/数据库）混为一谈，那么我们可以使用：

JDBC Testing Support Test Annotations (@Commit, @Rollback, @Sql*) Jdbc模板 ...

“默认”（假设为空）数据库的示例，已准备好（和@Rollback）：

package com.example.demo;

import static org.junit.jupiter.api.Assertions.*;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.annotation.Rollback;

@SpringBootTest
class StudentServiceIT  // .. here we try to test "all of our application" (as good as possible ..to the bone)

  @Autowired //! real "bean", no mock... this is only auxilary for this test, we could use some other method to prepare & verify
  private StudentRepository studentRepository;
  @Autowired //!! "real service"
  private StudentService studentService;

  @Test
  @Rollback // actually our test is "self-cleaning"...when no exceptions ;)
  void removeStudentByIdExists() throws StudentExistsException 
    // Given:
    Student student = new Student(1L, "Drake", "[e-mail]");
    studentRepository.save(student);

    // When:
    studentService.removeStudentByID(1L);

    // Then:
    assertFalse(studentRepository.findById(1L).isPresent());
  

  @Test
  @Rollback // in any case (if assumptions were wrong;)
  void removeStudentByIdNotExists() throws StudentExistsException 
    // Given:
    // nothing, we assume "empty db"

    // When:
    StudentExistsException thrown = assertThrows(
            StudentExistsException.class,
            () -> studentService.removeStudentByID(1L),
            "Expected testee.removeStudentByID to throw, but it didn't");
    // Then:
    assertNotNull(thrown);
    assertTrue(thrown.getMessage().contains("Student doesn't exist"));
  

（运行：mvn failsafe:integration-test）

感谢/参考：

JUnit 5: How to assert an exception is thrown? Mockito test a void method throws an exception Difference between @Mock and @InjectMocks

---

Complete Sample@github

【讨论】：

非常感谢。我为此苦苦挣扎了两天。我对此很陌生。即使我不了解您的代码的所有方面，我保证我会深入了解它，因为我已经理解了它的要点。我不能感谢你。没有其他人帮助过我。

欢迎您！ (young:) "padawan" :) 我添加了更多的 cmets（为了代码，在帖子中；）...

【参考方案2】：

我就是这样做的，让我知道它是否很好。 :)

@Test
    public void removeStudentByIdTest() throws StudentExistsException 
        Student student = new Student(1, "Drake", "[e-mail]");
        when(studentRepo.existsById(student.getId())).thenReturn(true);
        studentService.removeStudentByID(student.getId());
        verify(studentRepo).deleteById((long) 1);