# StopIteration: 

- **ID:** `python/unittest-mock-side-effect-iterator-exhausted`
- **领域:** python
- **类别:** runtime_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

一个 mock 的 side_effect 设置为迭代器（例如列表），但被调用的次数超过了迭代器中的项目数。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| 3.8 | active | — | — |
| 3.12 | active | — | — |

## 解决方案

1. **** (90% 成功率)
   ```
   def side_effect(*args, **kwargs):
    while True:
        yield 'value'

mock.side_effect = side_effect()
   ```
2. **** (95% 成功率)
   ```
   mock.assert_called_once()  # or assert_called_with
This will fail earlier with a clearer message if called too many times.
   ```

## 无效尝试

- **** — This may mask the real issue of unexpected extra calls. (80% 失败率)
- **** — Changes behavior and may hide bugs. (70% 失败率)