Convert usage of hardcoded namespace types

into their STI equivalent names.  For example,
`type: 'Group'` would become `type: Group.sti_name`

This is because we are now overriding the STI name for namespaces.  So
we should really use those values rather than hardcoding them.

app/models/custom_emoji.rb

@@ -5,7 +5,7 @@ class CustomEmoji < ApplicationRecord
 
   belongs_to :namespace, inverse_of: :custom_emoji
 
-  belongs_to :group, -> { where(type: 'Group') }, foreign_key: 'namespace_id'
+  belongs_to :group, -> { where(type: Group.sti_name) }, foreign_key: 'namespace_id'
   belongs_to :creator, class_name: "User", inverse_of: :created_custom_emoji
 
   # For now only external emoji are supported. See https://gitlab.com/gitlab-org/gitlab/-/issues/230467

app/models/customer_relations/contact.rb

@@ -5,7 +5,7 @@ class CustomerRelations::Contact < ApplicationRecord
 
   self.table_name = "customer_relations_contacts"
 
-  belongs_to :group, -> { where(type: 'Group') }, foreign_key: 'group_id'
+  belongs_to :group, -> { where(type: Group.sti_name) }, foreign_key: 'group_id'
   belongs_to :organization, optional: true
 
   strip_attributes! :phone, :first_name, :last_name

app/models/customer_relations/organization.rb

@@ -5,7 +5,7 @@ class CustomerRelations::Organization < ApplicationRecord
 
   self.table_name = "customer_relations_organizations"
 
-  belongs_to :group, -> { where(type: 'Group') }, foreign_key: 'group_id'
+  belongs_to :group, -> { where(type: Group.sti_name) }, foreign_key: 'group_id'
 
   strip_attributes! :name
 

app/models/members/group_member.rb

@@ -43,7 +43,7 @@ class GroupMember < Member
 
   # Because source_type is `Namespace`...
   def real_source_type
-    'Group'
+    Group.sti_name
   end
 
   def notifiable_options

app/models/namespace.rb

@@ -138,11 +138,11 @@ class Namespace < ApplicationRecord
   class << self
     def sti_class_for(type_name)
       case type_name
-      when 'Group'
+      when Group.sti_name
         Group
-      when 'Project'
+      when Namespaces::ProjectNamespace.sti_name
         Namespaces::ProjectNamespace
-      when 'User'
+      when Namespaces::UserNamespace.sti_name
         # TODO: We create a normal Namespace until
         #       https://gitlab.com/gitlab-org/gitlab/-/merge_requests/68894 is ready
         Namespace

app/models/packages/composer/cache_file.rb

@@ -9,7 +9,7 @@ module Packages
 
       mount_file_store_uploader Packages::Composer::CacheUploader
 
-      belongs_to :group, -> { where(type: 'Group') }, foreign_key: 'namespace_id'
+      belongs_to :group, -> { where(type: Group.sti_name) }, foreign_key: 'namespace_id'
       belongs_to :namespace
 
       validates :namespace, presence: true

app/models/project.rb

@@ -159,7 +159,7 @@ class Project < ApplicationRecord
   # Relations
   belongs_to :pool_repository
   belongs_to :creator, class_name: 'User'
-  belongs_to :group, -> { where(type: 'Group') }, foreign_key: 'namespace_id'
+  belongs_to :group, -> { where(type: Group.sti_name) }, foreign_key: 'namespace_id'
   belongs_to :namespace
   # Sync deletion via DB Trigger to ensure we do not have
   # a project without a project_namespace (or vice-versa)
@@ -851,7 +851,7 @@ class Project < ApplicationRecord
     end
 
     def group_ids
-      joins(:namespace).where(namespaces: { type: 'Group' }).select(:namespace_id)
+      joins(:namespace).where(namespaces: { type: Group.sti_name }).select(:namespace_id)
     end
 
     # Returns ids of projects with issuables available for given user

ee/spec/helpers/billing_plans_helper_spec.rb

@@ -167,7 +167,7 @@ RSpec.describe BillingPlansHelper do
   end
 
   describe '#use_new_purchase_flow?' do
-    where type: ['Group', nil],
+    where type: [Group.sti_name, nil],
       plan: Plan.all_plans,
       trial_active: [true, false]
 
@@ -183,7 +183,7 @@ RSpec.describe BillingPlansHelper do
       subject { helper.use_new_purchase_flow?(namespace) }
 
       it do
-        result = type == 'Group' && (plan == Plan::FREE || trial_active)
+        result = type == Group.sti_name && (plan == Plan::FREE || trial_active)
 
         is_expected.to be(result)
       end
@@ -349,7 +349,7 @@ RSpec.describe BillingPlansHelper do
     let(:plan) { double('Plan') }
 
     it 'is upgradable' do
-      group = double('Group', upgradable?: true)
+      group = double(Group.sti_name, upgradable?: true)
 
       expect(helper).to receive(:plan_upgrade_url)
 
@@ -357,7 +357,7 @@ RSpec.describe BillingPlansHelper do
     end
 
     it 'is purchasable' do
-      group = double('Group', upgradable?: false)
+      group = double(Group.sti_name, upgradable?: false)
 
       expect(helper).to receive(:plan_purchase_url)
       helper.plan_purchase_or_upgrade_url(group, plan)

spec/factories/groups.rb

@@ -4,7 +4,7 @@ FactoryBot.define do
   factory :group, class: 'Group', parent: :namespace do
     sequence(:name) { |n| "group#{n}" }
     path { name.downcase.gsub(/\s/, '_') }
-    type { 'Group' }
+    type { Group.sti_name }
     owner { nil }
     project_creation_level { ::Gitlab::Access::MAINTAINER_PROJECT_ACCESS }
 

spec/models/namespace_spec.rb

@@ -7,6 +7,10 @@ RSpec.describe Namespace do
   include GitHelpers
   include ReloadHelpers
 
+  let_it_be(:group_sti_name) { Group.sti_name }
+  let_it_be(:project_sti_name) { Namespaces::ProjectNamespace.sti_name }
+  let_it_be(:user_sti_name) { Namespaces::UserNamespace.sti_name }
+
   let!(:namespace) { create(:namespace, :with_namespace_settings) }
   let(:gitlab_shell) { Gitlab::Shell.new }
   let(:repository_storage) { 'default' }
@@ -38,20 +42,22 @@ RSpec.describe Namespace do
     context 'validating the parent of a namespace' do
       using RSpec::Parameterized::TableSyntax
 
+      # rubocop:disable Lint/BinaryOperatorWithIdenticalOperands
       where(:parent_type, :child_type, :error) do
-        nil         | 'User'      | nil
-        nil         | 'Group'     | nil
-        nil         | 'Project'   | 'must be set for a project namespace'
-        'Project'   | 'User'      | 'project namespace cannot be the parent of another namespace'
-        'Project'   | 'Group'     | 'project namespace cannot be the parent of another namespace'
-        'Project'   | 'Project'   | 'project namespace cannot be the parent of another namespace'
-        'Group'     | 'User'      | 'cannot not be used for user namespace'
-        'Group'     | 'Group'     | nil
-        'Group'     | 'Project'   | nil
-        'User'      | 'User'      | 'cannot not be used for user namespace'
-        'User'      | 'Group'     | 'user namespace cannot be the parent of another namespace'
-        'User'      | 'Project'   | nil
-      end
+        nil                      | ref(:user_sti_name)      | nil
+        nil                      | ref(:group_sti_name)     | nil
+        nil                      | ref(:project_sti_name)   | 'must be set for a project namespace'
+        ref(:project_sti_name)   | ref(:user_sti_name)      | 'project namespace cannot be the parent of another namespace'
+        ref(:project_sti_name)   | ref(:group_sti_name)     | 'project namespace cannot be the parent of another namespace'
+        ref(:project_sti_name)   | ref(:project_sti_name)   | 'project namespace cannot be the parent of another namespace'
+        ref(:group_sti_name)     | ref(:user_sti_name)      | 'cannot not be used for user namespace'
+        ref(:group_sti_name)     | ref(:group_sti_name)     | nil
+        ref(:group_sti_name)     | ref(:project_sti_name)   | nil
+        ref(:user_sti_name)      | ref(:user_sti_name)      | 'cannot not be used for user namespace'
+        ref(:user_sti_name)      | ref(:group_sti_name)     | 'user namespace cannot be the parent of another namespace'
+        ref(:user_sti_name)      | ref(:project_sti_name)   | nil
+      end
+      # rubocop:enable Lint/BinaryOperatorWithIdenticalOperands
 
       with_them do
         it 'validates namespace parent' do
@@ -170,7 +176,7 @@ RSpec.describe Namespace do
     let(:namespace) { Namespace.find(create(:namespace, type: namespace_type, parent: parent).id) }
 
     context 'creating a Group' do
-      let(:namespace_type) { 'Group' }
+      let(:namespace_type) { group_sti_name }
 
       it 'is valid' do
         expect(namespace).to be_a(Group)
@@ -180,7 +186,7 @@ RSpec.describe Namespace do
     end
 
     context 'creating a ProjectNamespace' do
-      let(:namespace_type) { 'Project' }
+      let(:namespace_type) { project_sti_name }
       let(:parent) { create(:group) }
 
       it 'is valid' do
@@ -191,7 +197,7 @@ RSpec.describe Namespace do
     end
 
     context 'creating a UserNamespace' do
-      let(:namespace_type) { 'User' }
+      let(:namespace_type) { user_sti_name }
 
       it 'is valid' do
         # TODO: We create a normal Namespace until