莫科托示例中的thenthrow（）方法

方案：测试控制器中的错误处理模拟服务异常

1. Spring Boot 应用代码

• Employee.java

package com.example.demo.model;

public class Employee {
    private String id;
    private String name;

    // constructors, getters, and setters
    public Employee(String id, String name) {
        this.id = id;
        this.name = name;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

• EmployeeNotFoundException.java

package com.example.demo.exception;

public class EmployeeNotFoundException extends RuntimeException {
    public EmployeeNotFoundException(String message) {
        super(message);
    }
}

• EmployeeService.java

package com.example.demo.service;

import com.example.demo.exception.EmployeeNotFoundException;
import com.example.demo.model.Employee;
import org.springframework.stereotype.Service;

@Service
public class EmployeeService {
    public Employee getEmployeeById(String id) {
        // 模拟员工不存在时抛出异常
        if ("0".equals(id)) {
            throw new EmployeeNotFoundException("Employee not found with id: " + id);
        }
        return new Employee(id, "John Doe");
    }
}

• EmployeeController.java

package com.example.demo.controller;

import com.example.demo.exception.EmployeeNotFoundException;
import com.example.demo.model.Employee;
import com.example.demo.service.EmployeeService;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/employees")
public class EmployeeController {
    private final EmployeeService employeeService;

    public EmployeeController(EmployeeService employeeService) {
        this.employeeService = employeeService;
    }

    @GetMapping("/{id}")
    public ResponseEntity<Employee> getEmployee(@PathVariable String id) {
        Employee employee = employeeService.getEmployeeById(id);
        return ResponseEntity.ok(employee);
    }

    // 全局异常处理
    @ExceptionHandler(EmployeeNotFoundException.class)
    public ResponseEntity<String> handleEmployeeNotFoundException(EmployeeNotFoundException ex) {
        return new ResponseEntity<>(ex.getMessage(), HttpStatus.NOT_FOUND);
    }
}

2. 使用 thenThrow() 的单元测试

• EmployeeControllerTest.java

package com.example.demo.controller;

import com.example.demo.exception.EmployeeNotFoundException;
import com.example.demo.model.Employee;
import com.example.demo.service.EmployeeService;
import org.junit.jupiter.api.Test;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import org.springframework.http.ResponseEntity;

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

class EmployeeControllerTest {

    @Mock
    private EmployeeService employeeService;

    @InjectMocks
    private EmployeeController employeeController;

    public EmployeeControllerTest() {
        MockitoAnnotations.openMocks(this); // 初始化 Mock 对象
    }

    @Test
    void testGetEmployee_Success() {
        // Arrange: 模拟服务方法逐一返回 Employee 对象
        when(employeeService.getEmployeeById("1")).thenReturn(new Employee("1", "John Doe"));

        // Act: 调用控制器方法
        ResponseEntity<Employee> response = employeeController.getEmployee("1");

        // Assert: 验证响应是否正确
        assertNotNull(response);
        assertEquals(200, response.getStatusCodeValue());
        assertEquals("John Doe", response.getBody().getName());

        // 验证服务方法被调用一次
        verify(employeeService, times(1)).getEmployeeById("1");
    }

    @Test
    void testGetEmployee_ThrowsException() {
        // Arrange: 模拟服务方法抛出异常
        when(employeeService.getEmployeeById("0")).thenThrow(new EmployeeNotFoundException("Employee not found with id: 0"));

        // Act & Assert: 验正确处理证异常是否正确
        assertThrows(EmployeeNotFoundException.class, () -> {
            employeeController.getEmployee("0");
        });

        // 验证服务方法被调用一次
        verify(employeeService, times(1)).getEmployeeById("0");
    }
}

说明:

thenThrow() 的用法：when(employeeService.getEmployeeById("0")).thenThrow(new EmployeeNotFoundException("Employee not found with id: 0")); 这一行代码模拟了当 getEmployeeById 方法传入 "0" 时抛出 EmployeeNotFoundException 异常。

单元测试包括两个测试用例：

• testGetEmployee_Success: 测试成功获取员工信息的情况。
• testGetEmployee_ThrowsException: 测试员工不存在，服务抛出异常，验证异常处理正确。

thenThrow() 的优点:

• 在不修改实际服务代码的情况下，模拟现实世界的错误处理。
• 对数据库错误、数据丢失等各种异常场景进行测试很方便API 失败等。
• 确保应用程序在出现错误时返回正确响应。

结论:

使用 Mockito 的 thenThrow() 在不依赖实际服务的情况下，该方法可以有效地测试异常处理逻辑。 这使得单元测试更加简单、可靠、易于维护。

以上是莫科托示例中thenthrow()方法的详细内容，请关注图灵教育的其他相关文章！