rubocop: a few fixes

* disable Layout/LineLength for now; it's not auto-correctable, and we have a
   LOT of violations
 * add a comment showing how to generate the final RuboCop enforced config
 * fix forcing of error level for gergich
 * fix boyscout mode always being on

Change-Id: Ie68b612f107e9e98b50a230a65ef2a616751362d
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/274008
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: August Thornton <august@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>

.rubocop.common.yml

@@ -20,6 +20,8 @@ Gemspec/OrderedDependencies:
 Layout/IndentationConsistency:
   Exclude:
     - "**/Gemfile.d/*" # we purposely indent dependent gems
+Layout/LineLength:
+  Enabled: false
 
 Lint/Debugger:
   Severity: error

.rubocop.enforced.yml

@@ -9,6 +9,9 @@ AllCops:
 
 <%=
 
+# if you want to see what this all evaluates to, you can run
+# `require 'erb'; puts ERB.new(File.read(".rubocop.enforced.yml")).result(binding)` from IRB
+
 # keys are cops you want to opt in for (nil being all cops)
 # values are an array of directories to opt in for (nil being all directories)
 OPT_IN = {

script/linter.rb

@@ -87,7 +87,6 @@ class Linter
               :campsite_mode,
               :command,
               :comment_post_processing,
-              :default_boyscout_mode,
               :custom_comment_generation,
               :env_sha,
               :file_regex,
@@ -164,7 +163,7 @@ class Linter
     if gerrit_patchset
       if boyscout_mode
         processed_comments.each do |comment|
-          comment[:severity] = :error
+          comment[:severity] = 'error'
         end
       end
       publish_gergich_comments(processed_comments)

script/rlint

@@ -15,7 +15,7 @@ linter_options = {
   campsite_mode: false,
   append_files_to_command: true,
   severe_levels: [],
-  default_boyscout_mode: false,
+  boyscout_mode: false,
   heavy_mode_proc: proc do |ruby_files|
     args = ruby_files
     args_index = ARGV.index('--')

script/stylelint

@@ -9,8 +9,7 @@ linter_options = {
   format: 'stylelint',
   command: 'node_modules/.bin/stylelint',
   campsite_mode: false,
-  append_files_to_command: true,
-  default_boyscout_mode: false
+  append_files_to_command: true
 }
 
 stylelint = Linter.new(linter_options)