Enable frozen string for spec/views

Partially addresses:

https://gitlab.com/gitlab-org/gitlab/issues/27703

app/helpers/diff_helper.rb

@@ -60,11 +60,16 @@ module DiffHelper
     if line.blank?
       " ".html_safe
     else
-      # We can't use `sub` because the HTML-safeness of `line` will not survive.
-      line[0] = '' if line.start_with?('+', '-', ' ')
+      # `sub` and substring-ing would destroy HTML-safeness of `line`
+      if line.start_with?('+', '-', ' ')
+        line.dup.tap do |line|
+          line[0] = ''
+        end
+      else
         line
       end
     end
+  end
 
   def parallel_diff_discussions(left, right, diff_file)
     return unless @grouped_diff_discussions

spec/config/smime_signature_settings_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe SmimeSignatureSettings do

spec/helpers/diff_helper_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe DiffHelper do

spec/views/admin/dashboard/index.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'admin/dashboard/index.html.haml' do

spec/views/admin/sessions/new.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'admin/sessions/new.html.haml' do

spec/views/ci/status/_badge.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'ci/status/_badge' do

spec/views/dashboard/projects/_blank_state_admin_welcome.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'dashboard/projects/_blank_state_admin_welcome.html.haml' do

spec/views/dashboard/projects/_nav.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'dashboard/projects/_nav.html.haml' do

spec/views/devise/shared/_signin_box.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'devise/shared/_signin_box' do

spec/views/errors/access_denied.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'errors/access_denied' do

spec/views/events/event/_push.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'events/event/_push.html.haml' do

spec/views/groups/_home_panel.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'groups/_home_panel' do

spec/views/groups/edit.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'groups/edit.html.haml' do

spec/views/help/instance_configuration.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'help/instance_configuration' do

spec/views/layouts/_head.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'layouts/_head' do

spec/views/layouts/nav/sidebar/_admin.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'layouts/nav/sidebar/_admin' do

spec/views/layouts/nav/sidebar/_project.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'layouts/nav/sidebar/_project' do

spec/views/notify/pipeline_failed_email.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'notify/pipeline_failed_email.html.haml' do

spec/views/notify/pipeline_success_email.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'notify/pipeline_success_email.html.haml' do

spec/views/profiles/show.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'profiles/show' do

spec/views/projects/_home_panel.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/_home_panel' do

spec/views/projects/blob/_viewer.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/blob/_viewer.html.haml' do

spec/views/projects/buttons/_dropdown.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/buttons/_dropdown' do

spec/views/projects/ci/lints/show.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/ci/lints/show' do

spec/views/projects/commit/_commit_box.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/commit/_commit_box.html.haml' do

spec/views/projects/commit/branches.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/commit/branches.html.haml' do

spec/views/projects/commit/show.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/commit/show.html.haml' do

spec/views/projects/commits/_commit.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/commits/_commit.html.haml' do

spec/views/projects/diffs/_stats.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/diffs/_stats.html.haml' do

spec/views/projects/diffs/_viewer.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/diffs/_viewer.html.haml' do

spec/views/projects/edit.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/edit' do

spec/views/projects/environments/terminal.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/environments/terminal' do

spec/views/projects/imports/new.html.haml_spec.rb

+# frozen_string_literal: true
+
 require "spec_helper"
 
 describe "projects/imports/new.html.haml" do

spec/views/projects/issues/_related_branches.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/issues/_related_branches' do

spec/views/projects/jobs/_build.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/ci/jobs/_build' do

spec/views/projects/jobs/_generic_commit_status.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/generic_commit_statuses/_generic_commit_status.html.haml' do

spec/views/projects/jobs/show.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/jobs/show' do

spec/views/projects/merge_requests/_commits.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/merge_requests/_commits.html.haml' do

spec/views/projects/merge_requests/creations/_new_submit.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/merge_requests/creations/_new_submit.html.haml' do

spec/views/projects/merge_requests/diffs/_diffs.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/merge_requests/diffs/_diffs.html.haml' do

spec/views/projects/merge_requests/edit.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/merge_requests/edit.html.haml' do

spec/views/projects/merge_requests/show.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/merge_requests/show.html.haml' do

spec/views/projects/notes/_more_actions_dropdown.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/notes/_more_actions_dropdown' do

spec/views/projects/pages_domains/show.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/pages_domains/show' do

spec/views/projects/pipeline_schedules/_pipeline_schedule.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/pipeline_schedules/_pipeline_schedule' do

spec/views/projects/pipelines/_stage.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/pipelines/_stage' do

spec/views/projects/services/_form.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/services/_form' do

spec/views/projects/settings/ci_cd/_autodevops_form.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/settings/ci_cd/_autodevops_form' do

spec/views/projects/tags/index.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/tags/index' do

spec/views/projects/tree/_tree_row.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/tree/_tree_row' do

spec/views/projects/tree/show.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'projects/tree/show' do

spec/views/shared/milestones/_issuable.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'shared/milestones/_issuable.html.haml' do

spec/views/shared/milestones/_issuables.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'shared/milestones/_issuables.html.haml' do

spec/views/shared/milestones/_top.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'shared/milestones/_top.html.haml' do

spec/views/shared/notes/_form.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'shared/notes/_form' do

spec/views/shared/projects/_project.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'shared/projects/_project.html.haml' do

spec/workers/update_project_statistics_worker_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe UpdateProjectStatisticsWorker do