add rubocop to CI / bump min ruby to 2.5

[jhoblitt]

Note that this is a breaking change the bump the minimum ruby version from 2.4 -> 2.5.

[codecov]

Codecov Report

Merging #33 (ee249e1) into master (d9aa3e9) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master      #33   +/-   ##
=======================================
  Coverage   91.75%   91.75%           
=======================================
  Files           1        1           
  Lines          97       97           
=======================================
  Hits           89       89           
  Misses          8        8           

Impacted Files	Coverage Δ
lib/beaker/module_install_helper.rb	91.75% <100.00%> (ø)

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[jhoblitt]

This should be more or less the minimum changes to get rubocop running as part of regular CI. Obviously, the rubocop configuration needs to updated. However, I'd suggest being pragmatic and "some linting" is better than "perfect linting". I'm willing to take the action item to apply a voxpupuli wide rubocop cop config to this repo if/when it is agreed upon.

[bastelfreak]

this is a major change. 2.5 is eol since 2022-03-31 as well. the question is if we want to drop it as well. thats the version that puppet 6 ships. maybe keeping it untill end of 2022 is okay.

[jhoblitt]

We should probably adopt a voxpupuli wide policy on when to drop ruby 2.5 (and 2.6). Normally I would say it should be dropped as soon as it is EOL but it sounds like puppet 6 will be supported until Feb of 2023: https://puppet.com/docs/puppet/7/platform_lifecycle.html

I am in favor of dropping support for 2.6 on 2022-03-31 or even now since there is no major puppet version tied to it.

[ekohl]

For what it's worth: it's my goal to retire this gem for Vox Pupupli's use. https://github.com/voxpupuli/beaker_puppet_helpers will replace this, beaker-puppet and beaker-puppet_install_helper. voxpupuli/voxpupuli-acceptance#31 is my WIP to convert.

[jhoblitt]

@bastelfreak @ekohl What should we do with this PR?

[ekohl]

I'll admit I never got around to completing the replacement of the gem entirely, so I don't mind moving forward with this.

[jhoblitt]

@ekohl OK - I'm trying to cut down on the pile of open PRs I need to review. I'll go ahead and merge this since the only concern was if we should also drop support for ruby 2.5.