python module_error ai_generated true

AttributeError: <module 'myapp.services' from '/app/services.py'> does not have the attribute 'requests'

ID: python/unittest-mock-patch-target-not-found

Also available as: JSON · Markdown · 中文
80%Fix Rate
90%Confidence
0Evidence
2024-01-19First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
3.8 active — — —
3.11 active — — —
3.12 active — — —

Root Cause

unittest.mock.patch targets the name where it is looked up, not where it is defined. If services.py does `import requests` and calls `requests.get`, patch 'myapp.services.requests.get'. If it does `from requests import get`, patch 'myapp.services.get'.

generic

中文

unittest.mock.patch 针对的是名称被查找的位置，而非定义位置。若 services.py 使用 `import requests` 并调用 `requests.get`，应 patch 'myapp.services.requests.get'；若使用 `from requests import get`，则应 patch 'myapp.services.get'。

Workarounds

  1. 95% success 
    Identify the binding style in the SUT and patch accordingly:
  # if SUT: import requests
  @patch('myapp.services.requests')
  def test_get(mock_req): ...
  # if SUT: from requests import get
  @patch('myapp.services.get')
  def test_get(mock_get): ...
  2. 90% success 
    Use pytest-mock's mocker fixture which resolves the same lookup semantics:
  def test_get(mocker):
      mocker.patch('myapp.services.requests.get')

Dead Ends

Common approaches that don't work:

  1. 75% fail

    Patches the global requests module, not the reference the SUT uses; the real network call still fires.

  2. 80% fail

    Creates a separate binding; the SUT's binding remains untouched.