don`t parse compat properties as fixtures

[RonnyPfannschmidt]

Fix #2701

its tricky to trigger those warnings under normal circumstances as they happen before pytest hooks into the warnings system

python -W always -m pytest testing/test_tmpdir.py --collectonly could be used to trigger them for example on the cli

[codecov]

Codecov Report

Merging #4164 into master will decrease coverage by 0.01%.
The diff coverage is 50%.

@@            Coverage Diff             @@
##           master    #4164      +/-   ##
==========================================
- Coverage   95.87%   95.85%   -0.02%     
==========================================
  Files         109      109              
  Lines       24626    24610      -16     
  Branches     2395     2395              
==========================================
- Hits        23609    23591      -18     
- Misses        721      722       +1     
- Partials      296      297       +1

Flag	Coverage Δ
#docs	29.04% <50%> (+0.02%)	⬆️
#doctesting	29.04% <50%> (+0.02%)	⬆️
#linting	29.04% <50%> (+0.02%)	⬆️
#linux	95.64% <50%> (-0.02%)	⬇️
#nobyte	91.37% <50%> (-0.66%)	⬇️
#numpy	41.65% <50%> (-51.38%)	⬇️
#pexpect	41.65% <50%> (+0.03%)	⬆️
#py27	94.04% <50%> (ø)	⬆️
#py34	92.21% <50%> (-0.11%)	⬇️
#py35	92.35% <50%> (+0.01%)	⬆️
#py36	93.98% <50%> (-0.02%)	⬇️
#py37	92.34% <50%> (ø)	⬆️
#trial	41.65% <50%> (-51.38%)	⬇️
#windows	93.38% <50%> (-0.76%)	⬇️
#xdist	93.72% <50%> (-0.18%)	⬇️

Impacted Files	Coverage Δ
src/_pytest/fixtures.py	97.12% <50%> (-0.25%)	⬇️
src/_pytest/pathlib.py	89.26% <0%> (-0.36%)	⬇️
src/_pytest/_code/source.py	90.65% <0%> (-0.09%)	⬇️
testing/test_pathlib.py
testing/test_paths.py	100% <0%> (ø)

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[coveralls]

Coverage increased (+0.02%) to 94.037% when pulling 877a4ab on RonnyPfannschmidt:nowarn-session-attributes into 17655b5 on pytest-dev:master.

[nicoddemus]

Hi @RonnyPfannschmidt, this seems to be working fine, why is it a RFC? Seems like it gets rid of the warnings about compat-properties during fixture collection quite nicely. 👍

[RonnyPfannschmidt]

@nicoddemus mainly because i skipped on tests and the docs

[nicoddemus]

Oh OK, I was under an erroneous definition of what RFC meant. 😁

[RonnyPfannschmidt]

no, i was ^^