Check `has_parent?` for determining validation type

app/models/namespace.rb

@@ -220,6 +220,10 @@ class Namespace < ActiveRecord::Base
     Project.inside_path(full_path)
   end
 
+  def has_parent?
+    parent.present?
+  end
+
   private
 
   def repository_storage_paths

app/validators/namespace_validator.rb

@@ -74,7 +74,7 @@ class NamespaceValidator < ActiveModel::EachValidator
                                preview blob blame raw files create_dir find_file
                                artifacts graphs refs badges objects folders file])
 
-  STRICT_RESERVED = (TOP_LEVEL_ROUTES | WILDCARD_ROUTES)
+  STRICT_RESERVED = (TOP_LEVEL_ROUTES | WILDCARD_ROUTES).freeze
 
   def self.valid_full_path?(full_path)
     path_segments = full_path.split('/')
@@ -120,8 +120,8 @@ class NamespaceValidator < ActiveModel::EachValidator
 
   def validation_type(record)
     case record
-    when Group
-      record.parent_id ? :wildcard : :top_level
+    when Namespace
+      record.has_parent? ? :wildcard : :top_level
     when Project
       :wildcard
     else

spec/models/namespace_spec.rb

@@ -47,6 +47,7 @@ describe Namespace, models: true do
   describe "Respond to" do
     it { is_expected.to respond_to(:human_name) }
     it { is_expected.to respond_to(:to_param) }
+    it { is_expected.to respond_to(:has_parent?) }
   end
 
   describe '#to_param' do