python type_error ai_generated true

AttributeError: Mock object has no attribute 'commit'

ID: python/unittest-mock-spec-missing-attribute

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80%Fix Rate
87%Confidence
0Evidence
2024-12-05First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
3.11 active — — —
3.12 active — — —

Root Cause

A Mock created with spec= or autospec= restricts attributes to the spec target. The code under test accesses an attribute not present on the spec, raising AttributeError.

generic

中文

使用 spec= 或 autospec= 创建的 Mock 将属性限制为 spec 目标上的属性。被测代码访问 spec 上不存在的属性时抛出 AttributeError。

Workarounds

  1. 90% success 
    from unittest.mock import patch
@patch('app.repo.Connection', autospec=True)
def test_save(mock_conn_cls):
    inst = mock_conn_cls.return_value
    inst.commit.return_value = None
    save()
    inst.commit.assert_called_once()
  2. 88% success 
    from unittest.mock import create_autospec
mock_conn = create_autospec(Connection, instance=True)
mock_conn.commit()  # allowed because Connection.commit exists

Dead Ends

Common approaches that don't work:

  1. 70% fail

    Disables typo detection and signature validation; tests pass with wrong method names, hiding real bugs.

  2. 60% fail

    Violates spec contract; the mock no longer reflects the real interface and future signature changes go unnoticed.