missleading error on getfuncargvalue for parameterized fixture

[pytestbot]

Originally reported by: Nikolaus Rath (BitBucket: nikratio, GitHub: nikratio)

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The attached meta-test-case results in

#!

    @pytest.fixture(params=(0,1,2))
    def param1(request):
>       return request.param
E       AttributeError: 'SubRequest' object has no attribute 'param'

with pytest from Mercurial tip.

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• Bitbucket: https://bitbucket.org/pytest-dev/pytest/issue/460

[pytestbot]

Original comment by Matthias Geier (BitBucket: geier, GitHub: geier):

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I get the same error when trying to create a fixture that concatenates two or more other fixtures (see my question on stackoverflow).

It's possible to have a fixture using a fixture using a fixture and so on, but it doesn't seem to be possible if parametrized fixtures are involved.

[pytestbot]

Original comment by Matthias Geier (BitBucket: geier, GitHub: geier):

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Here's my code example (without classes) that shows the same error:

#!python

import pytest

@pytest.fixture(params=[1, 2, 3])
def lower(request):
    return "i" * request.param

@pytest.fixture(params=[1, 2])
def upper(request):
    return "I" * request.param

@pytest.fixture(params=['lower', 'upper'])
def all(request):
    return request.getfuncargvalue(request.param)

def test_all(all):
    assert 0, all

Is there a way to make this work?

[pytestbot]

Original comment by Fayaz Khan (BitBucket: fayaz, GitHub: fayaz):

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In my case, the fixture seems to be failing because it shares name with a parameter on the test.

#!python

import pytest


@pytest.fixture(params=(0, 1, 2))
def param1(request):
    return request.param


@pytest.mark.parametrize('param1b', (1, 2))
def test_method(param1, param1b):
    assert param1 >= 0

Try changing the name param1b to param2 or something else, and it would work.

[pytestbot]

Original comment by Markus Unterwaditzer (BitBucket: untitaker, GitHub: untitaker):

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@Fayaz I have just discovered this issue as well and filed #745 because it doesn't seem to have anything to do with nested fixture requests.

[tomviner]

@RonnyPfannschmidt any reason this is listed as backward compatibility? Is request.getfuncargvalue deprecated? I'm hitting this issue with an on/off settings flipper fixture being used by a fixture that uses request.getfuncargvalue.

A minimal test case, equivalent of the one above:

import pytest

@pytest.fixture(params=[0])
def fix_with_param(request):
    print request.param

@pytest.fixture
def get_named_fixture(request):
    return request.getfuncargvalue('fix_with_param')

def test_thing(get_named_fixture):
    pass

Result is same as above: AttributeError: 'SubRequest' object has no attribute 'param'

[RonnyPfannschmidt]

that kind of usage should raise an error
'getfuncargvalue` cannnot ever work for parameter requests

[RonnyPfannschmidt]

this is a rather bad case,
since its also possible to hit this one indirectly

[tomviner]

Yeah I can see that using getfuncargvalue in a fixture can't start multiplying the cases, like params do. In fact it seems as difficult as supporting unittest subtests (#1367).

I think a better error than AttributeError: 'SubRequest' object has no attribute 'param' would be good.

[RonnyPfannschmidt]

its a completely different dimension than subtests ^^

subtests happen by design within a test

this case is requesting something that should have been parametrized before the test within the test and without parameters

[tomviner]

Fair enough. But we're agreed on needing a better error message?