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py.test does not correctly import modules from conftest - fails with ConftestImportFailure: ModuleNotFound

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pytest fails to import modules even though these modules import fine under the vanilla python interpreter. Especially modules imported from conftest fails to resolve. ImportErrori is raised when pytest tries to rewrite assert information in modules.

An example traceback:

================================================================================================================================================ test session starts ================================================================================================================================================
platform darwin -- Python 3.6.2, pytest-3.8.1, py-1.5.4, pluggy-0.7.1 -- /yyy/venv/bin/python3.6
cachedir: .pytest_cache
rootdir: /yyy/corporategovernance, inifile: setup.cfg
plugins: timeout-1.3.1, cov-2.5.1, populus-1.9.0, flaky-3.4.0, celery-4.1.0, splinter-1.8.5+headless
collecting 0 items / 1 errors                                                                                                                                                                                                                                                                                       
====================================================================================================================================================== ERRORS =======================================================================================================================================================
_________________________________________________________________________________________________________________________________ ERROR collecting corporategovernance/__init__.py __________________________________________________________________________________________________________________________________
../venv/lib/python3.6/site-packages/_pytest/config/__init__.py:381: in _getconftestmodules
    return self._path2confmods[path]
E   KeyError: local('/xxx/tests')

During handling of the above exception, another exception occurred:
../venv/lib/python3.6/site-packages/_pytest/config/__init__.py:412: in _importconftest
    return self._conftestpath2mod[conftestpath]
E   KeyError: local('/xxx/tests/conftest.py')

During handling of the above exception, another exception occurred:
../venv/lib/python3.6/site-packages/_pytest/config/__init__.py:418: in _importconftest
    mod = conftestpath.pyimport()
../venv/lib/python3.6/site-packages/py/_path/local.py:668: in pyimport
    __import__(modname)
../venv/lib/python3.6/site-packages/_pytest/assertion/rewrite.py:290: in load_module
    six.exec_(co, mod.__dict__)
corporategovernance/tests/conftest.py:4: in <module>
    import corporategovernance.backend
E   ModuleNotFoundError: No module named 'corporategovernance.backend'

During handling of the above exception, another exception occurred:
../venv/lib/python3.6/site-packages/_pytest/runner.py:201: in __init__
    self.result = func()
../venv/lib/python3.6/site-packages/_pytest/runner.py:261: in <lambda>
    call = CallInfo(lambda: list(collector.collect()), "collect")
../venv/lib/python3.6/site-packages/_pytest/python.py:624: in collect
    for x in self._collectfile(path):
../venv/lib/python3.6/site-packages/_pytest/python.py:579: in _collectfile
    ihook = self.gethookproxy(path)
../venv/lib/python3.6/site-packages/_pytest/python.py:568: in gethookproxy
    my_conftestmodules = pm._getconftestmodules(fspath)
../venv/lib/python3.6/site-packages/_pytest/config/__init__.py:395: in _getconftestmodules
    mod = self._importconftest(conftestpath)
../venv/lib/python3.6/site-packages/_pytest/config/__init__.py:431: in _importconftest
    raise ConftestImportFailure(conftestpath, sys.exc_info())
E   _pytest.config.ConftestImportFailure: ModuleNotFoundError("No module named 'corporategovernance.backend'",)
E     File "/yyy/venv/lib/python3.6/site-packages/_pytest/assertion/rewrite.py", line 290, in load_module
E       six.exec_(co, mod.__dict__)
E     File "/xxx/tests/conftest.py", line 4, in <module>
E       import corporategovernance.backend
===Flaky Test Report===

How to resolve?

like image 847
Mikko Ohtamaa Avatar asked Oct 01 '18 11:10

Mikko Ohtamaa


People also ask

What is Conftest PY in pytest?

conftest.py is where you setup test configurations and store the testcases that are used by test functions. The configurations and the testcases are called fixture in pytest.

What is a Conftest?

Conftest is a utility to help you write tests against structured configuration data. For instance, you could write tests for your Kubernetes configurations, Tekton pipeline definitions, Terraform code, Serverless configs or any other structured data.

Where do I put pytest files?

While the pytest discovery mechanism can find tests anywhere, pytests must be placed into separate directories from the product code packages. These directories may either be under the project root or under the Python package.


1 Answers

pytest may be picky if you have __init__.py files under your tests folder and subfolders. This may cause pytest to resolve Python modules in incorrect order under certain circumstances.

The workaround is to remove all __init__.py files under tests.

like image 136
Mikko Ohtamaa Avatar answered Nov 14 '22 23:11

Mikko Ohtamaa