python config_error ai_generated true

ValueError: id 数量不正确：3 而不是 2

ValueError: Incorrect number of ids: 3 instead of 2

ID: python/pytest-mark-parametrize-ids-mismatch

其他格式: JSON · Markdown 中文 · English
80%修复率
87%置信度
0证据数
2024-02-22首次发现

版本兼容性

版本状态引入弃用备注
3.x active — — —
7.x active — — —
8.x active — — —

根因分析

在 @pytest.mark.parametrize 中，`ids` 列表长度必须与参数集的数量匹配（而不是参数个数）。提供过多或过少的 id 会引发 ValueError。

English

In @pytest.mark.parametrize, the `ids` list length must match the number of parameter sets (not the number of arguments). Supplying too many or too few ids raises ValueError.

generic

解决方案

  1. 98% 成功率 
    @pytest.mark.parametrize(
    'a,b',
    [(1, 2), (3, 4)],
    ids=['small', 'large'],  # 2 ids for 2 tuples
)
def test_add(a, b):
    ...
  2. 90% 成功率 
    def idfn(val):
    return f'v={val}'

@pytest.mark.parametrize('x', [1, 2, 3], ids=idfn)
def test_x(x):
    ...

无效尝试

常见但无效的做法:

  1. 85% 失败

    pytest expects an iterable of id strings (or a callable); a single string is treated as an iterable of characters, producing confusing ids and possibly a length mismatch.

  2. 30% 失败

    Works but loses readable test names; not a real fix if the user needs custom ids for reporting.