Add `Account#actor_type_application?` query method (#33525)

app/models/account.rb

@@ -107,14 +107,14 @@ class Account < ApplicationRecord
   validates_with UniqueUsernameValidator, if: -> { will_save_change_to_username? }
 
   # Remote user validations, also applies to internal actors
-  validates :username, format: { with: USERNAME_ONLY_RE }, if: -> { (remote? || actor_type == 'Application') && will_save_change_to_username? }
+  validates :username, format: { with: USERNAME_ONLY_RE }, if: -> { (remote? || actor_type_application?) && will_save_change_to_username? }
 
   # Remote user validations
   validates :uri, presence: true, unless: :local?, on: :create
 
   # Local user validations
-  validates :username, format: { with: /\A[a-z0-9_]+\z/i }, length: { maximum: USERNAME_LENGTH_LIMIT }, if: -> { local? && will_save_change_to_username? && actor_type != 'Application' }
-  validates_with UnreservedUsernameValidator, if: -> { local? && will_save_change_to_username? && actor_type != 'Application' }
+  validates :username, format: { with: /\A[a-z0-9_]+\z/i }, length: { maximum: USERNAME_LENGTH_LIMIT }, if: -> { local? && will_save_change_to_username? && !actor_type_application? }
+  validates_with UnreservedUsernameValidator, if: -> { local? && will_save_change_to_username? && !actor_type_application? }
   validates :display_name, length: { maximum: DISPLAY_NAME_LENGTH_LIMIT }, if: -> { local? && will_save_change_to_display_name? }
   validates :note, note_length: { maximum: NOTE_LENGTH_LIMIT }, if: -> { local? && will_save_change_to_note? }
   validates :fields, length: { maximum: DEFAULT_FIELDS_SIZE }, if: -> { local? && will_save_change_to_fields? }
@@ -208,6 +208,10 @@ class Account < ApplicationRecord
     self.actor_type = ActiveModel::Type::Boolean.new.cast(val) ? 'Service' : 'Person'
   end
 
+  def actor_type_application?
+    actor_type == 'Application'
+  end
+
   def group?
     actor_type == 'Group'
   end

spec/models/account_spec.rb

@@ -80,6 +80,20 @@ RSpec.describe Account do
     end
   end
 
+  describe '#actor_type_application?' do
+    context 'when the actor is not of type application' do
+      subject { Fabricate.build :account, actor_type: 'Person' }
+
+      it { is_expected.to_not be_actor_type_application }
+    end
+
+    context 'when the actor is of type application' do
+      subject { Fabricate.build :account, actor_type: 'Application' }
+
+      it { is_expected.to be_actor_type_application }
+    end
+  end
+
   describe 'Local domain user methods' do
     subject { Fabricate(:account, domain: nil, username: 'alice') }