RFC Multiline logging

[twmr]

This adds support for aligned multi-line log messages:

What this change is doing is inserting white-space to all lines except the first of the "message" part of the log msg.

[codecov]

Codecov Report

Merging #4485 into features will decrease coverage by 0.03%.
The diff coverage is 56.25%.

@@             Coverage Diff              @@
##           features    #4485      +/-   ##
============================================
- Coverage     95.81%   95.77%   -0.04%     
============================================
  Files           111      111              
  Lines         25038    25063      +25     
  Branches       2463     2468       +5     
============================================
+ Hits          23989    24003      +14     
- Misses          738      746       +8     
- Partials        311      314       +3

Flag	Coverage Δ
#docs	29.3% <12.5%> (+0.06%)	⬆️
#doctesting	29.3% <12.5%> (+0.06%)	⬆️
#linting	29.3% <12.5%> (+0.06%)	⬆️
#linux	95.6% <56.25%> (-0.04%)	⬇️
#nobyte	92.51% <53.12%> (-0.05%)	⬇️
#numpy	93.23% <53.12%> (-0.05%)	⬇️
#pexpect	41.6% <12.5%> (-0.04%)	⬇️
#py27	93.84% <53.12%> (-0.03%)	⬇️
#py34	92.01% <43.75%> (+0.01%)	⬆️
#py35	92.03% <43.75%> (+0.01%)	⬆️
#py36	92.05% <43.75%> (+0.01%)	⬆️
#py37	93.96% <43.75%> (-0.04%)	⬇️
#trial	93.23% <53.12%> (-0.05%)	⬇️
#windows	94.02% <56.25%> (-0.07%)	⬇️
#xdist	93.88% <56.25%> (-0.06%)	⬇️

Impacted Files	Coverage Δ
src/_pytest/logging.py	91.77% <56.25%> (-4.29%)	⬇️
src/_pytest/cacheprovider.py	96.15% <0%> (-0.97%)	⬇️
src/_pytest/terminal.py	92.95% <0%> (+0.83%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e0ba1cb...d982dda. Read the comment docs.

[codecov]

Codecov Report

Merging #4485 into features will increase coverage by 0.02%.
The diff coverage is 56.25%.

@@             Coverage Diff              @@
##           features    #4485      +/-   ##
============================================
+ Coverage     95.74%   95.77%   +0.02%     
============================================
  Files           111      111              
  Lines         24951    25063     +112     
  Branches       2459     2468       +9     
============================================
+ Hits          23889    24003     +114     
+ Misses          748      746       -2     
  Partials        314      314

Flag	Coverage Δ
#docs	29.3% <12.5%> (+0.03%)	⬆️
#doctesting	29.3% <12.5%> (+0.03%)	⬆️
#linting	29.3% <12.5%> (+0.03%)	⬆️
#linux	95.6% <56.25%> (+0.02%)	⬆️
#nobyte	92.51% <53.12%> (+0.08%)	⬆️
#numpy	93.23% <53.12%> (+0.01%)	⬆️
#pexpect	41.6% <12.5%> (-0.16%)	⬇️
#py27	93.84% <53.12%> (+0.04%)	⬆️
#py34	92.01% <43.75%> (+0.16%)	⬆️
#py35	92.03% <43.75%> (+0.16%)	⬆️
#py36	92.05% <43.75%> (+0.15%)	⬆️
#py37	93.96% <43.75%> (+0.03%)	⬆️
#trial	93.23% <53.12%> (+0.01%)	⬆️
#windows	94.02% <56.25%> (+0.05%)	⬆️
#xdist	93.88% <56.25%> (+0.05%)	⬆️

Impacted Files	Coverage Δ
src/_pytest/logging.py	91.77% <56.25%> (-4.29%)	⬇️
src/_pytest/junitxml.py	93.37% <0%> (-1.03%)	⬇️
src/_pytest/debugging.py	81.25% <0%> (-0.51%)	⬇️
testing/python/metafunc.py	95.35% <0%> (-0.42%)	⬇️
src/_pytest/capture.py	93.42% <0%> (-0.25%)	⬇️
testing/python/raises.py	94.07% <0%> (-0.22%)	⬇️
testing/python/collect.py	99.15% <0%> (-0.22%)	⬇️
testing/test_warnings.py	98.64% <0%> (-0.17%)	⬇️
testing/test_parseopt.py	94.71% <0%> (-0.09%)	⬇️
src/_pytest/config/argparsing.py	88.15% <0%> (-0.06%)	⬇️
... and 23 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e63c7a1...4c846c8. Read the comment docs.

[blueyed]

Interesting.
I wonder though why not filename:lineno is used (to make it more condense), but that appears to not have changed here, or has it?

[blueyed]

Also just having "E", "W", "I" etc might be worthwile - think about smaller screen, e.g. 80 chars.

[twmr]

I like the idea about the short levelnames. However, colored short levelnames are currently not support by pytest, because the regex in the logging formatter does not support the levelname fmt '%(levelname).1s'.

At work I use a custom fmt string because I don't like the default one.

--log-cli-format='%(asctime)s.%(msecs)03d %(levelname).1s %(message)s'

Note the above one only looks good with a patched (support for single letter levelnames) pytest.

[s0undt3ch]

If this lands, can it be optional?

[twmr]

I think we should rather make the current integration of the log formatter a bit more extensible. What I have in mind is that the default formatter should be easily replaceable by a custom log formatter. Ideally we could create a collection of predefined log formatters in a new pytest package that can then be selected by name.

[s0undt3ch]

Even better then :)

[nicoddemus]

Hi @Thisch,

It has been a long time since it has last seen activity, plus we have made sweeping changes on master to drop Python 2.7 and 3.4 support, so this PR has some conflicts which require attention.

In order to clear up our queue and let us focus on the active PRs, I'm closing this PR for now.

Please don't consider this a rejection of your PR, we just want to get this out of sight until you have the time to tackle this again. If you get around to work on this in the future, please don't hesitate in re-opening this!

Thanks for your work, the team definitely appreciates it!