private string InitialiseManagerAndLogin(ExternalFileSecurityManager manager, string userName)
 {
     manager.Files = new string[]
         {
             GenerateUsersFile()
         };
     manager.Initialise();
     LoginRequest credentials = new LoginRequest(userName);
     credentials.AddCredential(LoginRequest.PasswordCredential, "whoareyou");
     string session = manager.Login(credentials);
     Assert.IsFalse(string.IsNullOrEmpty(session), "Session has not been allocated");
     return session;
 }