KeyError: 'testpaths' exception raised when using --override-ini command line option

[mbukatov]

Summary of the issue

When I use --override-ini feature while specifying particular test to run, py.test crashes with KeyError: 'testpaths' exception.

Description of a reproducer

Create minimal test case in ~/tmp directory so that:

$ cd ~/tmp
$ ls
test_foo.py
$ cat test_foo.py
def test_foo():
    assert True

Execution of this test case works as expected:

$ py.test 
============================== test session starts ===============================
platform linux -- Python 3.5.1, pytest-3.0.4, py-1.4.31, pluggy-0.4.0
rootdir: /home/usmqe/tmp, inifile: 
collected 1 items 

test_foo.py .

============================ 1 passed in 0.01 seconds ===========================

And there are no problems with invocations listed below either:

• py.test test_foo.py
• py.test --override-ini xfail_strict=True

But when I both reconfigure any configuration option via --override-ini and specify a test case at the same time, py.test crashes:

$ py.test --override-ini xfail_strict=True test_foo.py 
Traceback (most recent call last):
  File "/home/usmqe/.local/lib/python3.5/site-packages/_pytest/config.py", line 1064, in getini
    return self._inicache[name]
KeyError: 'testpaths'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/usmqe/.local/bin/py.test", line 11, in <module>
    sys.exit(main())
  File "/home/usmqe/.local/lib/python3.5/site-packages/_pytest/config.py", line 47, in main
    config = _prepareconfig(args, plugins)
  File "/home/usmqe/.local/lib/python3.5/site-packages/_pytest/config.py", line 132, in _prepareconfig
    pluginmanager=pluginmanager, args=args)
  File "/home/usmqe/.local/lib/python3.5/site-packages/_pytest/vendored_packages/pluggy.py", line 745, in __call__
    return self._hookexec(self, self._nonwrappers + self._wrappers, kwargs)
  File "/home/usmqe/.local/lib/python3.5/site-packages/_pytest/vendored_packages/pluggy.py", line 339, in _hookexec
    return self._inner_hookexec(hook, methods, kwargs)
  File "/home/usmqe/.local/lib/python3.5/site-packages/_pytest/vendored_packages/pluggy.py", line 334, in <lambda>
    _MultiCall(methods, kwargs, hook.spec_opts).execute()
  File "/home/usmqe/.local/lib/python3.5/site-packages/_pytest/vendored_packages/pluggy.py", line 613, in execute
    return _wrapped_call(hook_impl.function(*args), self.execute)
  File "/home/usmqe/.local/lib/python3.5/site-packages/_pytest/vendored_packages/pluggy.py", line 250, in _wrapped_call
    wrap_controller.send(call_outcome)
  File "/home/usmqe/.local/lib/python3.5/site-packages/_pytest/helpconfig.py", line 32, in pytest_cmdline_parse
    config = outcome.get_result()
  File "/home/usmqe/.local/lib/python3.5/site-packages/_pytest/vendored_packages/pluggy.py", line 279, in get_result
    raise ex[1].with_traceback(ex[2])
  File "/home/usmqe/.local/lib/python3.5/site-packages/_pytest/vendored_packages/pluggy.py", line 265, in __init__
    self.result = func()
  File "/home/usmqe/.local/lib/python3.5/site-packages/_pytest/vendored_packages/pluggy.py", line 614, in execute
    res = hook_impl.function(*args)
  File "/home/usmqe/.local/lib/python3.5/site-packages/_pytest/config.py", line 882, in pytest_cmdline_parse
    self.parse(args)
  File "/home/usmqe/.local/lib/python3.5/site-packages/_pytest/config.py", line 1045, in parse
    args = self.getini('testpaths')
  File "/home/usmqe/.local/lib/python3.5/site-packages/_pytest/config.py", line 1066, in getini
    self._inicache[name] = val = self._getini(name)
  File "/home/usmqe/.local/lib/python3.5/site-packages/_pytest/config.py", line 1074, in _getini
    value = self._get_override_ini_value(name)
  File "/home/usmqe/.local/lib/python3.5/site-packages/_pytest/config.py", line 1123, in _get_override_ini_value
    (key, user_ini_value) = ini_config.split("=", 1)
ValueError: not enough values to unpack (expected 2, got 1)

Enviroment

I'm using Python 3.5.1 (from rh-python35 collection on RHEL 7):

$ python --version
Python 3.5.1
$ rpm -qf $(which python)
rh-python35-python-3.5.1-6.el7.x86_64

And Pytest 3.0.4:

$ py.test --version
This is pytest version 3.0.4, imported from /home/usmqe/.local/lib/python3.5/site-packages/pytest.py

The rest of python environment:

$ pip list
You are using pip version 7.1.0, however version 9.0.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
docutils (0.12)
Jinja2 (2.8)
MarkupSafe (0.23)
mrglog (0.1.1)
pip (7.1.0)
plumbum (1.6.2)
py (1.4.31)
pytest (3.0.4)
PyYAML (3.10)
requests (2.11.1)
setuptools (18.0.1)
virtualenv (13.1.2)

[mbukatov]

I reproduced this on Fedora 24 in clean virtualenv with packages listed below as well:

$ pip list --format=legacy
pip (9.0.1)
py (1.4.31)
pytest (3.0.4)
setuptools (29.0.1)
wheel (0.30.0a0)

[decentral1se]

Oh, that's because the code does (source):

(key, user_ini_value) = ini_config.split("=", 1)

@mbukatov, everything should work when you run:

$ pytest --override-ini=xfail_strict=True test_foo.py

Not sure if pytest supports --override-ini Foo as well as --override-ini=Foo? This should probably recommend to pass the = instead of blowing up. Will submit a PR once someone give some direction.

[nicoddemus]

Not sure if pytest supports --override-ini Foo as well as --override-ini=Foo?

Not sure either, I think argparse handles that.

This should probably recommend to pass the = instead of blowing up.

I agree, I think it is sensible to check if = is not present in the option value and raise an UsageError giving a hint about always prefer passing =.

[mbukatov]

@lwm thanks for looking into this

[decentral1se]

Not sure if pytest supports --override-ini Foo as well as --override-ini=Foo?

Not sure either, I think argparse handles that.

Yes, argparse handles this but only for parsing arguments to --override-ini, not the values of the arguments. I've added some changes in #2108.