# AssertionError: 1 != 2 : 测试结果依赖于执行顺序

- **ID:** `python/unittest-testcase-ordering-issue`
- **领域:** python
- **类别:** runtime_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

测试共享可变状态（例如全局变量或类属性）而没有适当的隔离，导致顺序依赖的失败。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| 3.8 | active | — | — |
| 3.9 | active | — | — |
| 3.10 | active | — | — |
| 3.11 | active | — | — |
| 3.12 | active | — | — |

## 解决方案

1. **** (95% 成功率)
   ```
   Use setUp() to initialize fresh state for each test: `def setUp(self): self.shared_var = 0`
   ```
2. **** (90% 成功率)
   ```
   Refactor tests to avoid shared state by using local variables or mocks.
   ```

## 无效尝试

- **** — This is a brittle workaround; any change in test discovery order can break tests again. (90% 失败率)
- **** — setUpClass runs once per class, not per test, so state can still leak between tests. (80% 失败率)