scrapy-loader-upkeep migration

[BurnzZ]

Covers these items in #11 :

• [x] code migration
• [x] test migration

NOTES:

• The tests for py3.5 are failing because of f-strings. Are we going to deprecate py3.5 soon?

[codecov[bot]]

Codecov Report

Merging #12 into master will increase coverage by 0.14%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #12      +/-   ##
==========================================
+ Coverage   98.00%   98.14%   +0.14%     
==========================================
  Files           4        4              
  Lines         251      270      +19     
==========================================
+ Hits          246      265      +19     
  Misses          5        5              

Impacted Files	Coverage Δ
itemloaders/__init__.py	97.67% <100.00%> (+0.28%)	:arrow_up:

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[kmike]

The tests for py3.5 are failing because of f-strings. Are we going to deprecate py3.5 soon?

Currently Scrapy supports Python 3.5.1+ because it is Python availlable in Ubuntu 16.04 LTS. itemloaders should follow that, because Scrapy requires itemloders. We dropped Python 3.4 support just 7 months ago.

That said, there can be an argument to switch to Python 3.6. The share of 3.5 users, as reported by https://pypistats.org/packages/scrapy, is around 2-3%, which is not that large. This is better to be discussed in Scrapy issue tracker.