Explicitly test that guest is able to search through the wiki

lib/gitlab/elastic/project_search_results.rb

@@ -69,6 +69,8 @@ module Gitlab
       end
 
       def wiki_blobs
+        return Kaminari.paginate_array([]) unless Ability.allowed?(@current_user, :read_wiki, project)
+
         if project.wiki_enabled? && !project.wiki.empty? && query.present?
           project.wiki.search(
             query,

spec/lib/gitlab/project_search_results_spec.rb

@@ -124,8 +124,8 @@ describe Gitlab::ProjectSearchResults, lib: true do
     context 'when wiki is internal' do
       let(:project) { create(:project, :public, :wiki_private) }
 
-      it 'finds wiki blobs for members' do
-        project.add_reporter(user)
+      it 'finds wiki blobs for guest' do
+        project.add_guest(user)
 
         is_expected.not_to be_empty
       end