Issue 460: Fail on getfuncargvalue(<fixture with params>)

[tomviner]

Fix for #460

Raise helpful failure message, when requesting parametrized fixture at runtime, e.g. with request.getfuncargvalue.

This now fails before getting to AttributeError: 'SubRequest' object has no attribute 'param'.

BACKWARD INCOMPAT: Previously these params were simply never defined. So a fixture decorated like @pytest.fixture(params=[0, 1, 2]) only runs once. Now a failure is raised.

[RonnyPfannschmidt]

source-path should be relative to the test root if possible

[The-Compiler]

This seems kind of weird - if I'm reading the docs correctly you can do inspect.getframeinfo(frame) and then have a namedtuple with filename and lineno attributes.

[coveralls]

Coverage increased (+0.005%) to 92.211% when pulling 435d68a on tomviner:issue460/parameterized-subrequest into d81ee9a on pytest-dev:master.

[nicoddemus]

This is not valid in py26, that's why CI failed. 😉

[coveralls]

Coverage increased (+0.009%) to 92.214% when pulling e5e91af on tomviner:issue460/parameterized-subrequest into 5d8d1db on pytest-dev:master.

[tomviner]

Added the commented changes

• used named tuple from inspect.getframeinfo
• made path relative to root dir and added test
• fixed python 2.6 .format needed {0}
• changed change log entry

[coveralls]

Coverage increased (+0.009%) to 92.214% when pulling 5854a71 on tomviner:issue460/parameterized-subrequest into 5d8d1db on pytest-dev:master.

[The-Compiler]

LGTM, but I'd rather not be the one deciding on the backwards compatibility break and if it's okay 😆 - as said, I think it's perfectly fine for 3.0.

[nicoddemus]

be the one deciding on the backwards compatibility break and if it's okay

Hmm which backward compatibility break?

[tomviner]

@The-Compiler @nicoddemus

be the one deciding on the backwards compatibility break and if it's okay

Hmm which backward compatibility break?

The fact that this previously silently failed to apply the params:

@pytest.fixture(params=[0, 1, 2])
def fix_with_param(request):
    print "I never call request.param"

def test_foo(request):
    request.getfuncargvalue('fix_with_param')

And now fails with the helpful error message.