Signal-boost side effect for prepare method

The method does not only prepare the relation (as the `prepare_relation`
suggests), but also triggers batch counting which in turn executes the
query as a side-effect.

This is being signal-boosted with renaming the method to `prepare!`.

We use it in places where we actually want both (preloading/batch
counting) to happen. In other places (projects API), we actually don't
want that and have the ability to split this into multiple steps now.

lib/api/entities.rb

@@ -176,7 +176,6 @@ module API
     end
 
     class BasicProjectDetails < ProjectIdentity
-      include ::API::ProjectsRelationBuilder
       include ::API::ProjectsBatchCounting
 
       expose :default_branch, if: -> (project, options) { Ability.allowed?(options[:current_user], :download_code, project) }
@@ -212,6 +211,14 @@ module API
       expose :namespace, using: 'API::Entities::NamespaceBasic'
       expose :custom_attributes, using: 'API::Entities::CustomAttribute', if: :with_custom_attributes
 
+      # This adds preloading to the query and executes batch counting
+      # Side-effect: The query will be executed during batch counting
+      def self.prepare!(projects_relation)
+        preload_relation(projects_relation).tap do |projects|
+          execute_batch_counting(projects)
+        end
+      end
+
       # rubocop: disable CodeReuse/ActiveRecord
       def self.preload_relation(projects_relation, options = {})
         # Preloading tags, should be done with using only `:tags`,
@@ -419,7 +426,7 @@ module API
           options: { only_owned: true }
         ).execute
 
-        Entities::Project.prepare_relation(projects)
+        Entities::Project.prepare!(projects)
       end
 
       expose :shared_projects, using: Entities::Project do |group, options|
@@ -429,7 +436,7 @@ module API
           options: { only_shared: true }
         ).execute
 
-        Entities::Project.prepare_relation(projects)
+        Entities::Project.prepare!(projects)
       end
     end
 

lib/api/groups.rb

@@ -231,7 +231,7 @@ module API
 
         projects, options = with_custom_attributes(projects, options)
 
-        present options[:with].prepare_relation(projects), options
+        present options[:with].prepare!(projects), options
       end
 
       desc 'Get a list of subgroups in this group.' do

lib/api/projects.rb

@@ -96,7 +96,7 @@ module API
 
         options[:with] = Entities::BasicProjectDetails if params[:simple]
 
-        projects = options[:with].prepare_relation(projects, options)
+        projects = options[:with].preload_relation(projects, options)
 
         [projects, options]
       end

lib/api/projects_relation_builder.rb

-# frozen_string_literal: true
-
-module API
-  module ProjectsRelationBuilder
-    extend ActiveSupport::Concern
-
-    class_methods do
-      # Prepare the given projects relation, e.g. perform preloading.
-      def prepare_relation(projects_relation, options = {})
-        preload_relation(projects_relation, options)
-      end
-
-      def preload_relation(projects_relation, options = {})
-        projects_relation
-      end
-    end
-  end
-end