Decrease PerceivedComplexity threshold step by step (from 18 to 10)

Description

By analogy with #28202 (moved) let's planning decreasing PerceivedComplexity step by step (from 18 to 10)

2017-04-24 data:

Rubocop default level is 7 => 112 offenses Some statistics on different benchmarks:

• PerceivedComplexity size 10 => 33 offences
• PerceivedComplexity size 12 => 11 offences
• PerceivedComplexity size 14 => 6 offences
• PerceivedComplexity size 16 => 3 offences

Proposal

I think that level 10 is achievable in the nearest future. So I prepared checklist for first steps.

Decrease it step by step (values in TODO were checked on 2 Oct 2017):

• Step to 17 - !13947 (merged)
  • no offences in CE and EE
• Step to 16 - https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/2874
  • refactor app/helpers/license_helper.rb:15:3 - EE - PerceivedComplexity = 17
  • refactor app/helpers/tree_helper.rb:111:3 - EE PerceivedComplexity = 17
• Step to 15 - !14160 (merged)
  • refactor app/models/event.rb:242:3 - PerceivedComplexity = 16
• Step to 14 - !14231
  • refactor app/helpers/projects_helper.rb:30:3 - PerceivedComplexity = 15
• Step to 13
  • refactor app/helpers/nav_helper.rb:10:3 - PerceivedComplexity = 14
  • refactor app/services/projects/create_service.rb:7:5 - PerceivedComplexity = 14
  • refactor lib/gitlab/diff/file.rb:235:7 - PerceivedComplexity = 14
  • refactor lib/gitlab/checks/change_access.rb:145:7 - EE PerceivedComplexity = 14

Links / references

Documentation blurb

(Write the start of the documentation of this feature here, include:

1. Why should someone use it; what's the underlying problem.
2. What is the solution.
3. How does someone use this

During implementation, this can then be copied and used as a starter for the documentation.)

/cc @rymai @grzesiek

Possible labels: Edge backstage meta