python type_error ai_generated true

TypeError: test_foo() 缺少 1 个必需的位置参数: 'mock_open'

TypeError: test_foo() missing 1 required positional argument: 'mock_open'

ID: python/unittest-patch-decorator-argument-order

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80%修复率
87%置信度
0证据数
2024-02-07首次发现

版本兼容性

版本状态引入弃用备注
3.8 active — — —
3.12 active — — —

根因分析

多个 @patch 装饰器按从下到上的顺序注入 mock，但测试签名按从上到下列出，导致参数绑定错误。

English

Multiple @patch decorators inject mocks in bottom-up order, but the test signature lists them top-down, so arguments are bound to the wrong parameters.

generic

解决方案

  1. 95% 成功率 
    @patch('myapp.db.open')
@patch('myapp.fs.read')
def test_foo(mock_read, mock_open):
    # mock_read corresponds to the bottom decorator
    ...
  2. 90% 成功率 
    def test_foo():
    with patch('myapp.fs.read') as mock_read, \
         patch('myapp.db.open') as mock_open:
        ...

无效尝试

常见但无效的做法:

  1. 50% 失败

    Fixes one test but the convention is undocumented; other tests in the file break the same way.

  2. 60% 失败

    Mocks are positional; *args swallows them but makes assertions awkward and hides binding bugs.