Add BaseContainerService as new base service

Extract utility methods out as module for sharing.
See https://gitlab.com/gitlab-org/gitlab/-/issues/216672

app/services/base_container_service.rb

+# frozen_string_literal: true
+
+# Base class, scoped by container (project or group)
+class BaseContainerService
+  include BaseServiceUtility
+
+  attr_reader :container, :current_user, :params
+
+  def initialize(container:, current_user: nil, params: {})
+    @container, @current_user, @params = container, current_user, params.dup
+  end
+end

app/services/base_service.rb

 # frozen_string_literal: true
 
+# This is the original root class for service related classes,
+# and due to historical reason takes a project as scope.
+# Later separate base classes for different scopes will be created,
+# and existing service will use these one by one.
+# After all are migrated, we can remove this class.
+#
+# TODO: New services should consider inheriting from
+#       BaseContainerService, or create new base class:
+#       https://gitlab.com/gitlab-org/gitlab/-/issues/216672
 class BaseService
-  include Gitlab::Allowable
+  include BaseServiceUtility
 
   attr_accessor :project, :current_user, :params
 
@@ -9,67 +18,5 @@ class BaseService
     @project, @current_user, @params = project, user, params.dup
   end
 
-  def notification_service
-    NotificationService.new
-  end
-
-  def event_service
-    EventCreateService.new
-  end
-
-  def todo_service
-    TodoService.new
-  end
-
-  def log_info(message)
-    Gitlab::AppLogger.info message
-  end
-
-  def log_error(message)
-    Gitlab::AppLogger.error message
-  end
-
-  def system_hook_service
-    SystemHooksService.new
-  end
-
   delegate :repository, to: :project
-
-  # Add an error to the specified model for restricted visibility levels
-  def deny_visibility_level(model, denied_visibility_level = nil)
-    denied_visibility_level ||= model.visibility_level
-
-    level_name = Gitlab::VisibilityLevel.level_name(denied_visibility_level).downcase
-
-    model.errors.add(:visibility_level, "#{level_name} has been restricted by your GitLab administrator")
-  end
-
-  def visibility_level
-    params[:visibility].is_a?(String) ? Gitlab::VisibilityLevel.level_value(params[:visibility]) : params[:visibility_level]
-  end
-
-  private
-
-  # Return a Hash with an `error` status
-  #
-  # message     - Error message to include in the Hash
-  # http_status - Optional HTTP status code override (default: nil)
-  # pass_back   - Additional attributes to be included in the resulting Hash
-  def error(message, http_status = nil, pass_back: {})
-    result = {
-      message: message,
-      status: :error
-    }.reverse_merge(pass_back)
-
-    result[:http_status] = http_status if http_status
-    result
-  end
-
-  # Return a Hash with a `success` status
-  #
-  # pass_back - Additional attributes to be included in the resulting Hash
-  def success(pass_back = {})
-    pass_back[:status] = :success
-    pass_back
-  end
 end

app/services/concerns/base_service_utility.rb

+# frozen_string_literal: true
+
+module BaseServiceUtility
+  extend ActiveSupport::Concern
+  include Gitlab::Allowable
+
+  ### Convenience service methods
+
+  def notification_service
+    NotificationService.new
+  end
+
+  def event_service
+    EventCreateService.new
+  end
+
+  def todo_service
+    TodoService.new
+  end
+
+  def system_hook_service
+    SystemHooksService.new
+  end
+
+  # Logging
+
+  def log_info(message)
+    Gitlab::AppLogger.info message
+  end
+
+  def log_error(message)
+    Gitlab::AppLogger.error message
+  end
+
+  # Add an error to the specified model for restricted visibility levels
+  def deny_visibility_level(model, denied_visibility_level = nil)
+    denied_visibility_level ||= model.visibility_level
+
+    level_name = Gitlab::VisibilityLevel.level_name(denied_visibility_level).downcase
+
+    model.errors.add(:visibility_level, "#{level_name} has been restricted by your GitLab administrator")
+  end
+
+  def visibility_level
+    params[:visibility].is_a?(String) ? Gitlab::VisibilityLevel.level_value(params[:visibility]) : params[:visibility_level]
+  end
+
+  private
+
+  # Return a Hash with an `error` status
+  #
+  # message     - Error message to include in the Hash
+  # http_status - Optional HTTP status code override (default: nil)
+  # pass_back   - Additional attributes to be included in the resulting Hash
+  def error(message, http_status = nil, pass_back: {})
+    result = {
+      message: message,
+      status: :error
+    }.reverse_merge(pass_back)
+
+    result[:http_status] = http_status if http_status
+    result
+  end
+
+  # Return a Hash with a `success` status
+  #
+  # pass_back - Additional attributes to be included in the resulting Hash
+  def success(pass_back = {})
+    pass_back[:status] = :success
+    pass_back
+  end
+end

spec/services/base_container_service_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe BaseContainerService do
+  let(:project) { Project.new }
+  let(:user) { User.new }
+
+  describe '#initialize' do
+    it 'accepts container and current_user' do
+      subject = described_class.new(container: project, current_user: user)
+
+      expect(subject.container).to eq(project)
+      expect(subject.current_user).to eq(user)
+    end
+
+    it 'treats current_user as optional' do
+      subject = described_class.new(container: project)
+
+      expect(subject.current_user).to be_nil
+    end
+  end
+end