pytester: testdir: set $HOME to tmpdir

[blueyed]

This avoids loading user configuration, which might interfere with test
results, e.g. a ~/.pdbrc.py with pdb++.

TODO:

• changelog

[codecov]

Codecov Report

Merging #4941 into features will increase coverage by 0.01%.
The diff coverage is 100%.

@@             Coverage Diff              @@
##           features    #4941      +/-   ##
============================================
+ Coverage     95.84%   95.85%   +0.01%     
============================================
  Files           113      113              
  Lines         25266    25266              
  Branches       2495     2495              
============================================
+ Hits          24216    24219       +3     
+ Misses          735      734       -1     
+ Partials        315      313       -2

Impacted Files	Coverage Δ
testing/test_pdb.py	99.09% <ø> (-0.01%)	⬇️
src/_pytest/pytester.py	90.69% <100%> (+0.02%)	⬆️
testing/test_junitxml.py	97.8% <100%> (-0.01%)	⬇️
src/_pytest/capture.py	93.7% <0%> (-0.45%)	⬇️
src/_pytest/terminal.py	91.8% <0%> (+0.81%)	⬆️

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[blueyed]

Pushed an update for @asottile (via https://bugs.python.org/issue36264) ;)
Does $USERPROFILE work like $HOME in this regard?

[asottile]

Pushed an update for @asottile (via https://bugs.python.org/issue36264) ;)
Does $USERPROFILE work like $HOME in this regard?

yep

[nicoddemus]

LGTM, missing only a CHANGELOG entry. 👍

[blueyed]

Pushed an update for @asottile (via https://bugs.python.org/issue36264) ;)
Does $USERPROFILE work like $HOME in this regard?

yep

Might be worth having a helper in monkeypatch for this, handling any future changes in this regard maybe.. what do you think?

[asottile]

Pushed an update for @asottile (via https://bugs.python.org/issue36264) ;)
Does $USERPROFILE work like $HOME in this regard?

yep

Might be worth having a helper in monkeypatch for this, handling any future changes in this regard maybe.. what do you think?

mayyyybe, seems pretty niche though

should this code do:

if sys.platform == 'nt':
    ...
else:
    ...

[blueyed]

Yeah - basically it would help with what Python expects to see I guess; which also means that it should set $HOME with older versions (before 3.8), if it has preference there.

added changelog

[asottile]

Yeah - basically it would help with what Python expects to see I guess; which also means that it should set $HOME with older versions (before 3.8), if it has preference there.

shrugs, I don't think we should add it (increase our maintenance surface area) until someone asks for it