# E       fixture 'db_connection' 未找到

- **ID:** `python/pytest-collection-fixture-not-found`
- **领域:** python
- **类别:** config_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

pytest 无法找到测试引用的 fixture。该 fixture 可能定义在测试 rootdir 之外的 conftest.py 中、拼写错误、未导入，或作用域限于 pytest 未收集的目录。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| 7.x | active | — | — |
| 8.x | active | — | — |

## 解决方案

1. **** (92% 成功率)
   ```
   # conftest.py at project root
import pytest
@pytest.fixture
def db_connection():
    conn = create_conn()
    yield conn
    conn.close()

# tests/test_x.py
def test_query(db_connection):
    assert db_connection.execute('SELECT 1').fetchone()
   ```
2. **** (85% 成功率)
   ```
   # tests/conftest.py
pytest_plugins = ['myapp.testing.fixtures']

# run with explicit rootdir
# pytest --rootdir=. tests/
   ```
3. **** (78% 成功率)
   ```
   pytest --fixtures -q | grep db_connection
# If missing, check conftest.py location and rootdir:
pytest --collect-only -q
   ```

## 无效尝试

- **** — Duplicates fixture logic across files, and if the fixture depends on session-scoped resources (DB, network), local copies break isolation and teardown. (60% 失败率)
- **** — PYTHONPATH affects import resolution, not pytest fixture discovery. conftest.py is discovered by walking up from rootdir, not via sys.path. (75% 失败率)