Merge branch 'rc-use-haml_lint' into 'master'

Use `haml_lint` for views linting

## What does this MR do?

Add HAML-linting to the GitLab codebase.

## What are the relevant issue numbers?

Closes #19984.

See merge request !6307

.gitlab-ci.yml

@@ -206,6 +206,7 @@ spinach 9 10 ruby21: *spinach-knapsack-ruby21
     - bundle exec $CI_BUILD_NAME
 
 rubocop: *exec
+rake haml_lint: *exec
 rake scss_lint: *exec
 rake brakeman: *exec
 rake flog: *exec

.haml-lint.yml

+# Whether to ignore frontmatter at the beginning of HAML documents for
+# frameworks such as Jekyll/Middleman
+skip_frontmatter: false
+exclude:
+  - 'vendor/**/*'
+  - 'spec/**/*'
+
+linters:
+  AltText:
+    enabled: false
+
+  ClassAttributeWithStaticValue:
+    enabled: false
+
+  ClassesBeforeIds:
+    enabled: false
+
+  ConsecutiveComments:
+    enabled: false
+
+  ConsecutiveSilentScripts:
+    enabled: false
+    max_consecutive: 2
+
+  EmptyObjectReference:
+    enabled: true
+
+  EmptyScript:
+    enabled: true
+
+  FinalNewline:
+    enabled: false
+    present: true
+
+  HtmlAttributes:
+    enabled: false
+
+  ImplicitDiv:
+    enabled: false
+
+  LeadingCommentSpace:
+    enabled: false
+
+  LineLength:
+    enabled: false
+    max: 80
+
+  MultilinePipe:
+    enabled: false
+
+  MultilineScript:
+    enabled: true
+
+  ObjectReferenceAttributes:
+    enabled: true
+
+  RuboCop:
+    enabled: false
+    # These cops are incredibly noisy when it comes to HAML templates, so we
+    # ignore them.
+    ignored_cops:
+      - Lint/BlockAlignment
+      - Lint/EndAlignment
+      - Lint/Void
+      - Metrics/LineLength
+      - Style/AlignParameters
+      - Style/BlockNesting
+      - Style/ElseAlignment
+      - Style/FileName
+      - Style/FinalNewline
+      - Style/FrozenStringLiteralComment
+      - Style/IfUnlessModifier
+      - Style/IndentationWidth
+      - Style/Next
+      - Style/TrailingBlankLines
+      - Style/TrailingWhitespace
+      - Style/WhileUntilModifier
+
+  RubyComments:
+    enabled: false
+
+  SpaceBeforeScript:
+    enabled: false
+
+  SpaceInsideHashAttributes:
+    enabled: false
+    style: space
+
+  Indentation:
+    enabled: true
+    character: space # or tab
+
+  TagName:
+    enabled: true
+
+  TrailingWhitespace:
+    enabled: false
+
+  UnnecessaryInterpolation:
+    enabled: false
+
+  UnnecessaryStringOutput:
+    enabled: false

Gemfile

@@ -298,6 +298,7 @@ group :development, :test do
   gem 'rubocop', '~> 0.41.2', require: false
   gem 'rubocop-rspec', '~> 1.5.0', require: false
   gem 'scss_lint', '~> 0.47.0', require: false
+  gem 'haml_lint', '~> 0.18.2', require: false
   gem 'simplecov', '0.12.0', require: false
   gem 'flog', '~> 4.3.2', require: false
   gem 'flay', '~> 2.6.1', require: false

Gemfile.lock

@@ -322,6 +322,13 @@ GEM
     grape-entity (0.4.8)
       activesupport
       multi_json (>= 1.3.2)
+    haml (4.0.7)
+      tilt
+    haml_lint (0.18.2)
+      haml (~> 4.0)
+      rake (>= 10, < 12)
+      rubocop (>= 0.36.0)
+      sysexits (~> 1.1)
     hamlit (2.6.1)
       temple (~> 0.7.6)
       thor
@@ -723,6 +730,7 @@ GEM
     stringex (2.5.2)
     sys-filesystem (1.1.6)
       ffi
+    sysexits (1.2.0)
     systemu (2.6.5)
     task_list (1.0.2)
       html-pipeline
@@ -866,6 +874,7 @@ DEPENDENCIES
   gon (~> 6.1.0)
   grape (~> 0.15.0)
   grape-entity (~> 0.4.2)
+  haml_lint (~> 0.18.2)
   hamlit (~> 2.6.1)
   health_check (~> 2.1.0)
   hipchat (~> 1.5.0)

lib/tasks/haml-lint.rake

+unless Rails.env.production?
+  require 'haml_lint/rake_task'
+
+  HamlLint::RakeTask.new
+end