Admin user model returns min password length

app/models/admin_user.rb

@@ -11,6 +11,10 @@ class AdminUser < User
 
   devise :database_authenticatable, :rememberable, :trackable, :validatable, :lockable
 
+  def self.min_password_length
+    Devise.password_length.min
+  end
+
   def to_s
     username
   end

spec/models/admin_user_spec.rb

@@ -33,4 +33,10 @@ RSpec.describe AdminUser do
       @admin_user.errors.full_messages.should match_array(["Password confirmation doesn't match Password"])
     end
   end
+
+  describe '::min_password_length' do
+    it 'returns minimum password length' do
+      expect(described_class.min_password_length).to eq(8)
+    end
+  end
 end