python data_error ai_generated true

AssertionError: Expected 'mock_method' to be called once. Called 2 times.

ID: python/pytest-mock-not-reset-between-tests

Also available as: JSON · Markdown · 中文
80%Fix Rate
88%Confidence
0Evidence
2024-09-05First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
3.x active — — —

Root Cause

A mock object was not reset between tests, so call counts accumulated from previous tests. This happens when mocks are defined at module level or shared via class attributes.

generic

中文

mock 对象在测试之间未重置，因此调用计数从先前测试累积。这发生在 mock 定义在模块级别或通过类属性共享时。

Workarounds

  1. 95% success 
    @pytest.fixture
def mock_service():
    return MagicMock()

def test_one(mock_service):
    mock_service.method()
    mock_service.method.assert_called_once()
  2. 93% success 
    def test_one(mocker):
    mock = mocker.patch('module.func')
    mock()
    mock.assert_called_once()

Dead Ends

Common approaches that don't work:

  1. 75% fail

    If a test fails before reaching the reset line, the mock remains dirty for the next test. Also error-prone to maintain.

  2. 85% fail

    This changes the assertion but does not fix the accumulated call count. The assertion will still fail.