Enable frozen string in rest of app/models/**/*.rb

Partially addresses #47424.

55 files changed, 122 insertions, 14 deletions

diff --git a/app/models/programming_language.rb b/app/models/programming_language.rb
index 400d6c407a7..0e667dac21e 100644
--- a/app/models/programming_language.rb
+++ b/app/models/programming_language.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProgrammingLanguage < ActiveRecord::Base
   validates :name, presence: true
   validates :color, allow_blank: false, color: true
diff --git a/app/models/project_services/asana_service.rb b/app/models/project_services/asana_service.rb
index 4f289e6e215..35c19049c04 100644
--- a/app/models/project_services/asana_service.rb
+++ b/app/models/project_services/asana_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'asana'
 
 class AsanaService < Service
diff --git a/app/models/project_services/assembla_service.rb b/app/models/project_services/assembla_service.rb
index 4234b8044e5..60575e45a90 100644
--- a/app/models/project_services/assembla_service.rb
+++ b/app/models/project_services/assembla_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class AssemblaService < Service
   prop_accessor :token, :subdomain
   validates :token, presence: true, if: :activated?
diff --git a/app/models/project_services/bamboo_service.rb b/app/models/project_services/bamboo_service.rb
index edc5c00d9c4..d502423726c 100644
--- a/app/models/project_services/bamboo_service.rb
+++ b/app/models/project_services/bamboo_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class BambooService < CiService
   include ReactiveService
 
diff --git a/app/models/project_services/bugzilla_service.rb b/app/models/project_services/bugzilla_service.rb
index e4e3a80976b..1a2bb6a171b 100644
--- a/app/models/project_services/bugzilla_service.rb
+++ b/app/models/project_services/bugzilla_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class BugzillaService < IssueTrackerService
   validates :project_url, :issues_url, :new_issue_url, presence: true, public_url: true, if: :activated?
 
diff --git a/app/models/project_services/buildkite_service.rb b/app/models/project_services/buildkite_service.rb
index 35884c4560c..43edfde851c 100644
--- a/app/models/project_services/buildkite_service.rb
+++ b/app/models/project_services/buildkite_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "addressable/uri"
 
 class BuildkiteService < CiService
diff --git a/app/models/project_services/builds_email_service.rb b/app/models/project_services/builds_email_service.rb
index 0c526b53d72..f2295a95b60 100644
--- a/app/models/project_services/builds_email_service.rb
+++ b/app/models/project_services/builds_email_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # This class is to be removed with 9.1
 # We should also by then remove BuildsEmailService from database
 class BuildsEmailService < Service
diff --git a/app/models/project_services/campfire_service.rb b/app/models/project_services/campfire_service.rb
index cb4af73807b..1d7877a1fb5 100644
--- a/app/models/project_services/campfire_service.rb
+++ b/app/models/project_services/campfire_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class CampfireService < Service
   prop_accessor :token, :subdomain, :room
   validates :token, presence: true, if: :activated?
@@ -82,7 +84,7 @@ class CampfireService < Service
     before = push[:before]
     after = push[:after]
 
-    message = ""
+    message = []
     message << "[#{project.full_name}] "
     message << "#{push[:user_name]} "
 
@@ -95,6 +97,6 @@ class CampfireService < Service
       message << "#{project.web_url}/compare/#{before}...#{after}"
     end
 
-    message
+    message.join
   end
 end
diff --git a/app/models/project_services/chat_message/base_message.rb b/app/models/project_services/chat_message/base_message.rb
index f710fa85b5d..8c68ddc40f2 100644
--- a/app/models/project_services/chat_message/base_message.rb
+++ b/app/models/project_services/chat_message/base_message.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'slack-notifier'
 
 module ChatMessage
diff --git a/app/models/project_services/chat_message/issue_message.rb b/app/models/project_services/chat_message/issue_message.rb
index 3273f41dbd2..0cdcfcf0237 100644
--- a/app/models/project_services/chat_message/issue_message.rb
+++ b/app/models/project_services/chat_message/issue_message.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ChatMessage
   class IssueMessage < BaseMessage
     attr_reader :title
diff --git a/app/models/project_services/chat_message/merge_message.rb b/app/models/project_services/chat_message/merge_message.rb
index f412b6833d9..58631e09538 100644
--- a/app/models/project_services/chat_message/merge_message.rb
+++ b/app/models/project_services/chat_message/merge_message.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ChatMessage
   class MergeMessage < BaseMessage
     attr_reader :merge_request_iid
diff --git a/app/models/project_services/chat_message/note_message.rb b/app/models/project_services/chat_message/note_message.rb
index 7f9486132e6..741474fb27b 100644
--- a/app/models/project_services/chat_message/note_message.rb
+++ b/app/models/project_services/chat_message/note_message.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ChatMessage
   class NoteMessage < BaseMessage
     attr_reader :note
diff --git a/app/models/project_services/chat_message/pipeline_message.rb b/app/models/project_services/chat_message/pipeline_message.rb
index 96fd23aede3..62aec4351db 100644
--- a/app/models/project_services/chat_message/pipeline_message.rb
+++ b/app/models/project_services/chat_message/pipeline_message.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ChatMessage
   class PipelineMessage < BaseMessage
     attr_reader :ref_type
diff --git a/app/models/project_services/chat_message/push_message.rb b/app/models/project_services/chat_message/push_message.rb
index 8d599c5f116..82be33a12a1 100644
--- a/app/models/project_services/chat_message/push_message.rb
+++ b/app/models/project_services/chat_message/push_message.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ChatMessage
   class PushMessage < BaseMessage
     attr_reader :after
diff --git a/app/models/project_services/chat_message/wiki_page_message.rb b/app/models/project_services/chat_message/wiki_page_message.rb
index d84b80f2de2..b605d289278 100644
--- a/app/models/project_services/chat_message/wiki_page_message.rb
+++ b/app/models/project_services/chat_message/wiki_page_message.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ChatMessage
   class WikiPageMessage < BaseMessage
     attr_reader :title
diff --git a/app/models/project_services/chat_notification_service.rb b/app/models/project_services/chat_notification_service.rb
index a60b4c7fd0d..c10ee07ccf4 100644
--- a/app/models/project_services/chat_notification_service.rb
+++ b/app/models/project_services/chat_notification_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Base class for Chat notifications services
 # This class is not meant to be used directly, but only to inherit from.
 class ChatNotificationService < Service
diff --git a/app/models/project_services/ci_service.rb b/app/models/project_services/ci_service.rb
index 82979c8bd34..f0ef2d925ab 100644
--- a/app/models/project_services/ci_service.rb
+++ b/app/models/project_services/ci_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Base class for CI services
 # List methods you need to implement to get your CI service
 # working with GitLab Merge Requests
diff --git a/app/models/project_services/custom_issue_tracker_service.rb b/app/models/project_services/custom_issue_tracker_service.rb
index 456c7f5cee2..b8f8072869c 100644
--- a/app/models/project_services/custom_issue_tracker_service.rb
+++ b/app/models/project_services/custom_issue_tracker_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class CustomIssueTrackerService < IssueTrackerService
   validates :project_url, :issues_url, :new_issue_url, presence: true, public_url: true, if: :activated?
 
diff --git a/app/models/project_services/deployment_service.rb b/app/models/project_services/deployment_service.rb
index 5b8320158fc..6dae4f3a4a6 100644
--- a/app/models/project_services/deployment_service.rb
+++ b/app/models/project_services/deployment_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Base class for deployment services
 #
 # These services integrate with a deployment solution like Kubernetes/OpenShift,
diff --git a/app/models/project_services/drone_ci_service.rb b/app/models/project_services/drone_ci_service.rb
index ab4e46da89f..158ae0bf255 100644
--- a/app/models/project_services/drone_ci_service.rb
+++ b/app/models/project_services/drone_ci_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class DroneCiService < CiService
   include ReactiveService
 
diff --git a/app/models/project_services/emails_on_push_service.rb b/app/models/project_services/emails_on_push_service.rb
index b604d860a87..fb73d430fb1 100644
--- a/app/models/project_services/emails_on_push_service.rb
+++ b/app/models/project_services/emails_on_push_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class EmailsOnPushService < Service
   boolean_accessor :send_from_committer_email
   boolean_accessor :disable_diffs
diff --git a/app/models/project_services/external_wiki_service.rb b/app/models/project_services/external_wiki_service.rb
index a4b1ef09e93..d2835c6ac82 100644
--- a/app/models/project_services/external_wiki_service.rb
+++ b/app/models/project_services/external_wiki_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ExternalWikiService < Service
   prop_accessor :external_wiki_url
 
diff --git a/app/models/project_services/flowdock_service.rb b/app/models/project_services/flowdock_service.rb
index da01ac1b7cf..2545df06f6b 100644
--- a/app/models/project_services/flowdock_service.rb
+++ b/app/models/project_services/flowdock_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "flowdock-git-hook"
 
 # Flow dock depends on Grit to compute the number of commits between two given
diff --git a/app/models/project_services/gemnasium_service.rb b/app/models/project_services/gemnasium_service.rb
index 8a6b0ed1a5f..67a92c441b1 100644
--- a/app/models/project_services/gemnasium_service.rb
+++ b/app/models/project_services/gemnasium_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "gemnasium/gitlab_service"
 
 class GemnasiumService < Service
diff --git a/app/models/project_services/gitlab_issue_tracker_service.rb b/app/models/project_services/gitlab_issue_tracker_service.rb
index 16e32a4139e..fa9abf58e62 100644
--- a/app/models/project_services/gitlab_issue_tracker_service.rb
+++ b/app/models/project_services/gitlab_issue_tracker_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class GitlabIssueTrackerService < IssueTrackerService
   include Gitlab::Routing
 
diff --git a/app/models/project_services/hangouts_chat_service.rb b/app/models/project_services/hangouts_chat_service.rb
index a8512c5f57c..272cd0f4e47 100644
--- a/app/models/project_services/hangouts_chat_service.rb
+++ b/app/models/project_services/hangouts_chat_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'hangouts_chat'
 
 class HangoutsChatService < ChatNotificationService
diff --git a/app/models/project_services/hipchat_service.rb b/app/models/project_services/hipchat_service.rb
index dce878e485f..66012f0da99 100644
--- a/app/models/project_services/hipchat_service.rb
+++ b/app/models/project_services/hipchat_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class HipchatService < Service
   include ActionView::Helpers::SanitizeHelper
 
@@ -108,7 +110,7 @@ class HipchatService < Service
     before = push[:before]
     after = push[:after]
 
-    message = ""
+    message = []
     message << "#{push[:user_name]} "
 
     if Gitlab::Git.blank_ref?(before)
@@ -132,7 +134,7 @@ class HipchatService < Service
       end
     end
 
-    message
+    message.join
   end
 
   def markdown(text, options = {})
@@ -165,11 +167,11 @@ class HipchatService < Service
     description = obj_attr[:description]
 
     issue_link = "<a href=\"#{issue_url}\">issue ##{issue_iid}</a>"
-    message = "#{user_name} #{state} #{issue_link} in #{project_link}: <b>#{title}</b>"
 
+    message = ["#{user_name} #{state} #{issue_link} in #{project_link}: <b>#{title}</b>"]
     message << "<pre>#{markdown(description)}</pre>"
 
-    message
+    message.join
   end
 
   def create_merge_request_message(data)
@@ -184,12 +186,11 @@ class HipchatService < Service
 
     merge_request_url = "#{project_url}/merge_requests/#{merge_request_id}"
     merge_request_link = "<a href=\"#{merge_request_url}\">merge request !#{merge_request_id}</a>"
-    message = "#{user_name} #{state} #{merge_request_link} in " \
-      "#{project_link}: <b>#{title}</b>"
+    message = ["#{user_name} #{state} #{merge_request_link} in " \
+      "#{project_link}: <b>#{title}</b>"]
 
     message << "<pre>#{markdown(description)}</pre>"
-
-    message
+    message.join
   end
 
   def format_title(title)
@@ -235,12 +236,11 @@ class HipchatService < Service
     end
 
     subject_html = "<a href=\"#{note_url}\">#{subject_type} #{subject_desc}</a>"
-    message = "#{user_name} commented on #{subject_html} in #{project_link}: "
+    message = ["#{user_name} commented on #{subject_html} in #{project_link}: "]
     message << title
 
     message << "<pre>#{markdown(note, ref: commit_id)}</pre>"
-
-    message
+    message.join
   end
 
   def create_pipeline_message(data)
diff --git a/app/models/project_services/irker_service.rb b/app/models/project_services/irker_service.rb
index 27bdf708c80..a783a314071 100644
--- a/app/models/project_services/irker_service.rb
+++ b/app/models/project_services/irker_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'uri'
 
 class IrkerService < Service
diff --git a/app/models/project_services/issue_tracker_service.rb b/app/models/project_services/issue_tracker_service.rb
index df6dcd90985..c7520d766a8 100644
--- a/app/models/project_services/issue_tracker_service.rb
+++ b/app/models/project_services/issue_tracker_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class IssueTrackerService < Service
   validate :one_issue_tracker, if: :activated?, on: :manual_change
 
diff --git a/app/models/project_services/jira_service.rb b/app/models/project_services/jira_service.rb
index 82d438d5378..cc98b3f5a41 100644
--- a/app/models/project_services/jira_service.rb
+++ b/app/models/project_services/jira_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class JiraService < IssueTrackerService
   include Gitlab::Routing
   include ApplicationHelper
diff --git a/app/models/project_services/kubernetes_service.rb b/app/models/project_services/kubernetes_service.rb
index 722642f6da7..bda1f67b8ff 100644
--- a/app/models/project_services/kubernetes_service.rb
+++ b/app/models/project_services/kubernetes_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 ##
 # NOTE:
 # We'll move this class to Clusters::Platforms::Kubernetes, which contains exactly the same logic.
diff --git a/app/models/project_services/mattermost_service.rb b/app/models/project_services/mattermost_service.rb
index 0362ed172c7..b8bc83b870e 100644
--- a/app/models/project_services/mattermost_service.rb
+++ b/app/models/project_services/mattermost_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class MattermostService < ChatNotificationService
   def title
     'Mattermost notifications'
diff --git a/app/models/project_services/mattermost_slash_commands_service.rb b/app/models/project_services/mattermost_slash_commands_service.rb
index 227d430083d..ca324f68d2d 100644
--- a/app/models/project_services/mattermost_slash_commands_service.rb
+++ b/app/models/project_services/mattermost_slash_commands_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class MattermostSlashCommandsService < SlashCommandsService
   include TriggersHelper
 
diff --git a/app/models/project_services/microsoft_teams_service.rb b/app/models/project_services/microsoft_teams_service.rb
index 99500caec0e..5b0e5fed092 100644
--- a/app/models/project_services/microsoft_teams_service.rb
+++ b/app/models/project_services/microsoft_teams_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class MicrosoftTeamsService < ChatNotificationService
   def title
     'Microsoft Teams Notification'
diff --git a/app/models/project_services/mock_ci_service.rb b/app/models/project_services/mock_ci_service.rb
index b89dc07a73e..6883976f0c8 100644
--- a/app/models/project_services/mock_ci_service.rb
+++ b/app/models/project_services/mock_ci_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # For an example companion mocking service, see https://gitlab.com/gitlab-org/gitlab-mock-ci-service
 class MockCiService < CiService
   ALLOWED_STATES = %w[failed canceled running pending success success_with_warnings skipped not_found].freeze
diff --git a/app/models/project_services/mock_deployment_service.rb b/app/models/project_services/mock_deployment_service.rb
index 59a3811ce5d..7ab1687f8ba 100644
--- a/app/models/project_services/mock_deployment_service.rb
+++ b/app/models/project_services/mock_deployment_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class MockDeploymentService < DeploymentService
   def title
     'Mock deployment'
diff --git a/app/models/project_services/mock_monitoring_service.rb b/app/models/project_services/mock_monitoring_service.rb
index ed0318c6b27..bcf8f1df5da 100644
--- a/app/models/project_services/mock_monitoring_service.rb
+++ b/app/models/project_services/mock_monitoring_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class MockMonitoringService < MonitoringService
   def title
     'Mock monitoring'
diff --git a/app/models/project_services/monitoring_service.rb b/app/models/project_services/monitoring_service.rb
index 9af68b4e821..1b530a8247b 100644
--- a/app/models/project_services/monitoring_service.rb
+++ b/app/models/project_services/monitoring_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Base class for monitoring services
 #
 # These services integrate with a deployment solution like Prometheus
diff --git a/app/models/project_services/packagist_service.rb b/app/models/project_services/packagist_service.rb
index ba62a5b7ac0..003884bb7ac 100644
--- a/app/models/project_services/packagist_service.rb
+++ b/app/models/project_services/packagist_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class PackagistService < Service
   prop_accessor :username, :token, :server
 
diff --git a/app/models/project_services/pipelines_email_service.rb b/app/models/project_services/pipelines_email_service.rb
index 4cf149ac044..6f39a5e6e83 100644
--- a/app/models/project_services/pipelines_email_service.rb
+++ b/app/models/project_services/pipelines_email_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class PipelinesEmailService < Service
   prop_accessor :recipients
   boolean_accessor :notify_only_broken_pipelines
diff --git a/app/models/project_services/pivotaltracker_service.rb b/app/models/project_services/pivotaltracker_service.rb
index 3476e7d2283..617e502b639 100644
--- a/app/models/project_services/pivotaltracker_service.rb
+++ b/app/models/project_services/pivotaltracker_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class PivotaltrackerService < Service
   API_ENDPOINT = 'https://www.pivotaltracker.com/services/v5/source_commits'.freeze
 
diff --git a/app/models/project_services/prometheus_service.rb b/app/models/project_services/prometheus_service.rb
index df4254e0523..509e5b6089b 100644
--- a/app/models/project_services/prometheus_service.rb
+++ b/app/models/project_services/prometheus_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class PrometheusService < MonitoringService
   include PrometheusAdapter
 
diff --git a/app/models/project_services/pushover_service.rb b/app/models/project_services/pushover_service.rb
index 8777a44b72f..4e48c348b45 100644
--- a/app/models/project_services/pushover_service.rb
+++ b/app/models/project_services/pushover_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class PushoverService < Service
   BASE_URI = 'https://api.pushover.net/1'.freeze
 
@@ -79,7 +81,7 @@ class PushoverService < Service
       end
 
     if data[:total_commits_count] > 0
-      message << "\nTotal commits count: #{data[:total_commits_count]}"
+      message = [message, "Total commits count: #{data[:total_commits_count]}"].join("\n")
     end
 
     pushover_data = {
diff --git a/app/models/project_services/redmine_service.rb b/app/models/project_services/redmine_service.rb
index 3721093a6d1..a80be4b06da 100644
--- a/app/models/project_services/redmine_service.rb
+++ b/app/models/project_services/redmine_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class RedmineService < IssueTrackerService
   validates :project_url, :issues_url, :new_issue_url, presence: true, public_url: true, if: :activated?
 
diff --git a/app/models/project_services/slack_service.rb b/app/models/project_services/slack_service.rb
index 71da0af75f6..482808255f9 100644
--- a/app/models/project_services/slack_service.rb
+++ b/app/models/project_services/slack_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class SlackService < ChatNotificationService
   def title
     'Slack notifications'
diff --git a/app/models/project_services/slack_slash_commands_service.rb b/app/models/project_services/slack_slash_commands_service.rb
index 1c3892a3f75..6c82e088231 100644
--- a/app/models/project_services/slack_slash_commands_service.rb
+++ b/app/models/project_services/slack_slash_commands_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class SlackSlashCommandsService < SlashCommandsService
   include TriggersHelper
 
diff --git a/app/models/project_services/slash_commands_service.rb b/app/models/project_services/slash_commands_service.rb
index 37ea45109ae..e3ab60adefd 100644
--- a/app/models/project_services/slash_commands_service.rb
+++ b/app/models/project_services/slash_commands_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Base class for Chat services
 # This class is not meant to be used directly, but only to inherrit from.
 class SlashCommandsService < Service
diff --git a/app/models/project_services/teamcity_service.rb b/app/models/project_services/teamcity_service.rb
index 802678147cf..eeeff5e802a 100644
--- a/app/models/project_services/teamcity_service.rb
+++ b/app/models/project_services/teamcity_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class TeamcityService < CiService
   include ReactiveService
 
diff --git a/app/models/protected_branch/merge_access_level.rb b/app/models/protected_branch/merge_access_level.rb
index e8d35ac326f..b0d5c64e931 100644
--- a/app/models/protected_branch/merge_access_level.rb
+++ b/app/models/protected_branch/merge_access_level.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProtectedBranch::MergeAccessLevel < ActiveRecord::Base
   include ProtectedBranchAccess
 end
diff --git a/app/models/protected_branch/push_access_level.rb b/app/models/protected_branch/push_access_level.rb
index 7a2e9e5ec5d..b2a88229853 100644
--- a/app/models/protected_branch/push_access_level.rb
+++ b/app/models/protected_branch/push_access_level.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProtectedBranch::PushAccessLevel < ActiveRecord::Base
   include ProtectedBranchAccess
 end
diff --git a/app/models/protected_tag/create_access_level.rb b/app/models/protected_tag/create_access_level.rb
index 6b6ab3d8279..b06e55fb5dd 100644
--- a/app/models/protected_tag/create_access_level.rb
+++ b/app/models/protected_tag/create_access_level.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProtectedTag::CreateAccessLevel < ActiveRecord::Base
   include ProtectedTagAccess
 
diff --git a/app/models/repository_language.rb b/app/models/repository_language.rb
index f467d4eafa3..b18142a2ac4 100644
--- a/app/models/repository_language.rb
+++ b/app/models/repository_language.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class RepositoryLanguage < ActiveRecord::Base
   belongs_to :project
   belongs_to :programming_language
diff --git a/app/models/site_statistic.rb b/app/models/site_statistic.rb
index 9c9c3172fe6..daac1c57db9 100644
--- a/app/models/site_statistic.rb
+++ b/app/models/site_statistic.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class SiteStatistic < ActiveRecord::Base
   # prevents the creation of multiple rows
   default_value_for :id, 1
diff --git a/app/models/storage/hashed_project.rb b/app/models/storage/hashed_project.rb
index 26b4b78ac64..90710f73fd3 100644
--- a/app/models/storage/hashed_project.rb
+++ b/app/models/storage/hashed_project.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Storage
   class HashedProject
     attr_accessor :project
diff --git a/app/models/storage/legacy_project.rb b/app/models/storage/legacy_project.rb
index 27cb388c702..9f6f19acb41 100644
--- a/app/models/storage/legacy_project.rb
+++ b/app/models/storage/legacy_project.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Storage
   class LegacyProject
     attr_accessor :project