diff --git a/lib/devise_kerberos_authenticatable/kerberos_adapter.rb b/lib/devise_kerberos_authenticatable/kerberos_adapter.rb
index 4f5ca1a..995df69 100644
--- a/lib/devise_kerberos_authenticatable/kerberos_adapter.rb
+++ b/lib/devise_kerberos_authenticatable/kerberos_adapter.rb
@@ -4,19 +4,26 @@ include Krb5Auth
 module Devise
   module KerberosAdapter
     def self.valid_credentials?(username, password)
-      if Rails.env.test? && username == 'test' && password == 'test' then
+      if test_environment? && username == 'test' && password == 'test' then
         return true
       end
 
       krb5 = Krb5.new
-      username_with_realm = "#{username}@#{::Devise.kerberos_realm}"
       begin
-        krb5.get_init_creds_password(username_with_realm, password)
+        krb5.get_init_creds_password(username_with_realm(username), password)
       rescue Krb5Auth::Krb5::Exception
         return false
       end
 
       return true
     end
+
+    def username_with_realm(username)
+      "#{username}@#{::Devise.kerberos_realm}"
+    end
+
+    def self.test_environment?
+      Rails.env.test? || Rails.env.development?
+    end
   end
 end