Add serializers for Integrations Project

https://gitlab.com/gitlab-org/gitlab/-/issues/218252
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/65207

app/controllers/admin/integrations_controller.rb

@@ -11,9 +11,10 @@ class Admin::IntegrationsController < Admin::ApplicationController
   def overrides
     respond_to do |format|
       format.json do
-        collection = Project.with_active_integration(integration.class).merge(::Integration.not_inherited)
+        projects = Project.with_active_integration(integration.class).merge(::Integration.not_inherited)
+        serializer = ::Integrations::ProjectSerializer.new.with_pagination(request, response)
 
-        render json: collection.page(params[:page]).per(20).to_json
+        render json: serializer.represent(projects)
       end
       # TODO frontend will add format.html
     end

app/serializers/integrations/project_entity.rb

+# frozen_string_literal: true
+
+module Integrations
+  class ProjectEntity < Grape::Entity
+    include RequestAwareEntity
+
+    expose :avatar_url
+    expose :full_name
+    expose :name
+
+    expose :full_path do |project|
+      project_path(project)
+    end
+  end
+end

app/serializers/integrations/project_serializer.rb

+# frozen_string_literal: true
+
+module Integrations
+  class ProjectSerializer < BaseSerializer
+    include WithPagination
+
+    entity Integrations::ProjectEntity
+  end
+end

spec/controllers/admin/integrations_controller_spec.rb

@@ -114,7 +114,8 @@ RSpec.describe Admin::IntegrationsController do
       subject
 
       expect(response).to have_gitlab_http_status(:ok)
-      expect(json_response).to contain_exactly(a_hash_including('id' => overridden_integration.project_id))
+      expect(response).to include_pagination_headers
+      expect(json_response).to contain_exactly(a_hash_including('full_name' => overridden_integration.project.full_name))
     end
   end
 end

spec/serializers/integrations/project_entity_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Integrations::ProjectEntity do
+  let_it_be(:project) { create(:project, :with_avatar) }
+
+  let(:entity) do
+    described_class.new(project)
+  end
+
+  context 'as json' do
+    include Gitlab::Routing.url_helpers
+
+    subject { entity.as_json }
+
+    it 'contains needed attributes' do
+      expect(subject).to include(
+        avatar_url: include('uploads'),
+        name: project.name,
+        full_path: project_path(project),
+        full_name: project.full_name
+      )
+    end
+  end
+end

spec/serializers/integrations/project_serializer_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Integrations::ProjectSerializer do
+  it 'represents Integrations::ProjectEntity entities' do
+    expect(described_class.entity_class).to eq(Integrations::ProjectEntity)
+  end
+end