python runtime_error ai_generated true

AttributeError: 'NoneType' object has no attribute 'get'

ID: python/pytest-patch-stopall-early

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80%Fix Rate
85%Confidence
0Evidence
2025-08-11First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
3.10 active — — —
3.12 active — — —

Root Cause

A test calls `patch.stopall()` in a `finally` block, which removes patches set up by `setUp` for subsequent tests in the same class. Later tests see the real (or None) object instead of the mock.

generic

中文

测试在 `finally` 块中调用 `patch.stopall()`，这会移除同一类中 `setUp` 为后续测试设置的 patch。后续测试看到的是真实对象（或 None），而不是 mock。

Workarounds

  1. 95% success 
    Use context managers or decorators so patches are scoped automatically:

@patch('mymod.dep')
def test_x(mock_dep):
    ...
  2. 90% success 
    Use `addCleanup` to stop patches at the right time:

self.addCleanup(patcher.stop)

Dead Ends

Common approaches that don't work:

  1. 80% fail

    tearDown runs after each test, so the same problem persists across tests in the class.

  2. 70% fail

    Hard to detect failure reliably; patches still leak between tests.