Use pprint.pformat on versions log message

[grammy-jiang]

This commit use pprint.pformat on overridden settings to keep consistent
with scrapy.middleware, for example:
Original:

2019-12-01 11:35:40 [scrapy.utils.log] INFO: Versions: lxml 4.3.4.0, libxml2 2.9.9, cssselect 1.0.3, parsel 1.5.1, w3lib 1.20.0, Twisted 19.2.1, Python 3.7.5 (default, Oct 17 2019, 12:16:48) - [GCC 9.2.1 20190827 (Red Hat 9.2.1-1)], pyOpenSSL 19.0.0 (OpenSSL 1.1.1c  28 May 2019), cryptography 2.7, Platform Linux-5.3.7-301.fc31.x86_64-x86_64-with-fedora-31-Thirty_One

Now:

2019-12-01 11:04:22 [scrapy.utils.log] INFO: Versions:
{'Platform': 'Linux-5.3.7-301.fc31.x86_64-x86_64-with-fedora-31-Thirty_One',
 'Python': '3.7.5 (default, Oct 17 2019, 12:16:48) - [GCC 9.2.1 20190827 (Red '
           'Hat 9.2.1-1)]',
 'Twisted': '19.2.1',
 'cryptography': '2.7',
 'cssselect': '1.0.3',
 'libxml2': '2.9.9',
 'lxml': '4.3.4.0',
 'parsel': '1.5.1',
 'pyOpenSSL': '19.0.0 (OpenSSL 1.1.1c  28 May 2019)',
 'w3lib': '1.20.0'}

[codecov]

Codecov Report

Merging #4203 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #4203      +/-   ##
==========================================
+ Coverage   83.73%   83.73%   +<.01%     
==========================================
  Files         165      165              
  Lines        9714     9715       +1     
  Branches     1446     1446              
==========================================
+ Hits         8134     8135       +1     
  Misses       1332     1332              
  Partials      248      248

Impacted Files	Coverage Δ
scrapy/utils/log.py	88.63% <100%> (+0.13%)	⬆️

[wRAR]

As seen in the provided example, this changes the order of components.

scrapy_components_versions() returns a list of tuples while the code creates a dict. Can you please fix this, maybe OrderedDict will help?

[grammy-jiang]

The order is changed by the pprint module, and disabling the sorted function inside pprint is only available in Python 3.8. Although a decorator can be added to fix this, this makes things too complicated. I want to keep the solution simple.

And with the help of OrderedDict, the output is like this:

2019-12-03 09:13:05 [scrapy.utils.log] INFO: Versions:
OrderedDict([('lxml', '4.4.2.0'),
             ('libxml2', '2.9.9'),
             ('cssselect', '1.1.0'),
             ('parsel', '1.5.2'),
             ('w3lib', '1.21.0'),
             ('Twisted', '19.10.0'),
             ('Python', '3.7.5 (default, Nov 27 2019, 16:53:22) - [GCC 7.4.0]'),
             ('pyOpenSSL', '18.0.0 (OpenSSL 1.1.0i  14 Aug 2018)'),
             ('cryptography', '2.3.1'),
             ('Platform',
              'Linux-5.0.0-36-generic-x86_64-with-debian-buster-sid')])

Emmm, which looks strange. I don't like this format break solution.

[Gallaecio]

We could write a private function just to print the desired output format from the versions iterable.

It think it’s either that or wait until we drop support for CPython 3.5.

[grammy-jiang]

Consider nobody raises an issue about this output format and it is quite minor problem, I think we should not do too much work just for this. We can just leave it until the minimum support version becomes Python 3.8.

[wRAR]

3.7 is almost EOL so we can now use sort_dicts=False.