# 无法实例化 @InjectMocks 字段 'service'，类型为 'class com.example.MyService'

- **ID:** `java/mockito-injectmocks-failure`
- **领域:** java
- **类别:** config_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

@InjectMocks 需要无参构造函数或构造函数注入，但类缺少无参构造函数或有歧义的构造函数。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| 8+ | active | — | — |

## 解决方案

1. **Provide a no-arg constructor in production class** (90% 成功率)
   ```
   public MyService() {
    // default constructor
}
   ```
2. **Use manual construction with mocks** (85% 成功率)
   ```
   MyService service = new MyService(mockDep1, mockDep2);
   ```

## 无效尝试

- **Adding @InjectMocks to a field with private constructor** — Mockito cannot instantiate the class. (70% 失败率)
- **Using @Spy on the same field** — Spy requires an instance; @InjectMocks is for creating instances. (50% 失败率)