_getconftestmodules: use functools.lru_cache

[blueyed]

Also renames _path2confmods to _dirpath2confmods for clarity (it is
expected to be a dirpath in _importconftest).

Merges master to avoid conflict with 63691f5 (which should have been done on features probably).

[nicoddemus]

There's a simple failure related to renaming the private attribute

[nicoddemus]

So the failing test on py27 is testing that we are caching _getconftestmodules. This patch makes the test pass:

diff --git a/src/_pytest/config/__init__.py b/src/_pytest/config/__init__.py
index 20c1e3ec..1124304a 100644
--- a/src/_pytest/config/__init__.py
+++ b/src/_pytest/config/__init__.py
@@ -395,6 +395,11 @@ class PytestPluginManager(PluginManager):
         else:
             directory = path

+        try:
+            return self._dirpath2confmods[directory]
+        except KeyError:
+            pass
+

But it kind of reduces the point of using lru_cache a bit, doesn't it?

I guess it is OK to apply the patch above (perhaps inside a if six.PY2 block to make it clear that is py2-only).

[blueyed]

Thanks, added it with if six.PY2.

[codecov]

Codecov Report

Merging #4247 into features will decrease coverage by 3.53%.
The diff coverage is 100%.

@@             Coverage Diff             @@
##           features   #4247      +/-   ##
===========================================
- Coverage     95.83%   92.3%   -3.54%     
===========================================
  Files           111     111              
  Lines         24777   24769       -8     
  Branches       2417    2414       -3     
===========================================
- Hits          23746   22862     -884     
- Misses          734    1512     +778     
- Partials        297     395      +98

Flag	Coverage Δ
#docs	?
#doctesting	?
#linting	?
#linux	92.3% <100%> (-3.33%)	⬇️
#nobyte	?
#numpy	?
#pexpect	?
#py27	?
#py34	92.1% <100%> (-0.07%)	⬇️
#py35	?
#py36	92.09% <100%> (-1.85%)	⬇️
#py37	?
#trial	?
#windows	?
#xdist	?

Impacted Files	Coverage Δ
src/_pytest/config/__init__.py	94.63% <100%> (-0.37%)	⬇️
testing/test_conftest.py	99.61% <100%> (ø)	⬆️
src/_pytest/_code/_py2traceback.py	20% <0%> (-71.12%)	⬇️
testing/test_pdb.py	42.19% <0%> (-52.95%)	⬇️
src/_pytest/debugging.py	53.19% <0%> (-31.92%)	⬇️
src/_pytest/unittest.py	74.01% <0%> (-20.34%)	⬇️
testing/python/approx.py	79.84% <0%> (-19.77%)	⬇️
src/_pytest/compat.py	78.07% <0%> (-18.72%)	⬇️
src/_pytest/recwarn.py	83.19% <0%> (-15.13%)	⬇️
src/_pytest/python_api.py	82.83% <0%> (-14.6%)	⬇️
... and 47 more

---

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[blueyed]

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