Move migrated? logic to PagesDeployment

* also add scope for finding migrated deployments

app/models/pages/lookup_path.rb

@@ -5,7 +5,6 @@ module Pages
     include Gitlab::Utils::StrongMemoize
 
     LegacyStorageDisabledError = Class.new(::StandardError)
-    MIGRATED_FILE_NAME = "_migrated.zip"
 
     def initialize(project, trim_prefix: nil, domain: nil)
       @project = project
@@ -55,7 +54,7 @@ module Pages
 
       return if deployment.file.file_storage? && !Feature.enabled?(:pages_serve_with_zip_file_protocol, project)
 
-      return if deployment.file.filename == MIGRATED_FILE_NAME && !Feature.enabled?(:pages_serve_from_migrated_zip, project)
+      return if deployment.migrated? && !Feature.enabled?(:pages_serve_from_migrated_zip, project)
 
       global_id = ::Gitlab::GlobalId.build(deployment, id: deployment.id).to_s
 

app/models/pages_deployment.rb

@@ -4,12 +4,15 @@
 class PagesDeployment < ApplicationRecord
   include FileStoreMounter
 
+  MIGRATED_FILE_NAME = "_migrated.zip"
+
   attribute :file_store, :integer, default: -> { ::Pages::DeploymentUploader.default_store }
 
   belongs_to :project, optional: false
   belongs_to :ci_build, class_name: 'Ci::Build', optional: true
 
   scope :older_than, -> (id) { where('id < ?', id) }
+  scope :migrated_from_legacy_storage, -> { where(file: MIGRATED_FILE_NAME) }
 
   validates :file, presence: true
   validates :file_store, presence: true, inclusion: { in: ObjectStorage::SUPPORTED_STORES }
@@ -25,6 +28,10 @@ class PagesDeployment < ApplicationRecord
     # this is to be adressed in https://gitlab.com/groups/gitlab-org/-/epics/589
   end
 
+  def migrated?
+    file.filename == MIGRATED_FILE_NAME
+  end
+
   private
 
   def set_size

spec/models/pages/lookup_path_spec.rb

@@ -124,22 +124,12 @@ RSpec.describe Pages::LookupPath do
 
         include_examples 'uses disk storage'
       end
-    end
 
       context 'when deployment were created during migration' do
         before do
-        FileUtils.mkdir_p File.join(project.pages_path, "public")
-        File.open(File.join(project.pages_path, "public/index.html"), "w") do |f|
-          f.write("Hello!")
-        end
-
-        expect(::Pages::MigrateLegacyStorageToDeploymentService.new(project).execute[:status]).to eq(:success)
-
-        project.reload
+          allow(deployment).to receive(:migrated?).and_return(true)
         end
 
-      let(:deployment) { project.pages_metadatum.pages_deployment }
-
         it 'uses deployment from object storage' do
           freeze_time do
             expect(source).to(
@@ -164,6 +154,7 @@ RSpec.describe Pages::LookupPath do
         end
       end
     end
+  end
 
   describe '#prefix' do
     it 'returns "/" for pages group root projects' do

spec/models/pages_deployment_spec.rb

@@ -26,6 +26,43 @@ RSpec.describe PagesDeployment do
     end
   end
 
+  describe '.migrated_from_legacy_storage' do
+    it 'only returns migrated deployments' do
+      project = create(:project)
+      migrated_deployment = create_migrated_deployment(project)
+      # create one other deployment
+      create(:pages_deployment, project: project)
+
+      expect(described_class.migrated_from_legacy_storage).to eq([migrated_deployment])
+    end
+  end
+
+  describe '#migrated?' do
+    it 'returns false for normal deployment' do
+      deployment = create(:pages_deployment)
+
+      expect(deployment.migrated?).to eq(false)
+    end
+
+    it 'returns true for migrated deployment' do
+      project = create(:project)
+      deployment = create_migrated_deployment(project)
+
+      expect(deployment.migrated?).to eq(true)
+    end
+  end
+
+  def create_migrated_deployment(project)
+    FileUtils.mkdir_p File.join(project.pages_path, "public")
+    File.open(File.join(project.pages_path, "public/index.html"), "w") do |f|
+      f.write("Hello!")
+    end
+
+    expect(::Pages::MigrateLegacyStorageToDeploymentService.new(project).execute[:status]).to eq(:success)
+
+    project.reload.pages_metadatum.pages_deployment
+  end
+
   describe 'default for file_store' do
     let(:project) { create(:project) }
     let(:deployment) do