Refactoring method to make it unit testing friendly
Following on what Magnus said in comments can you not inject the necessary dependencies.

For example:

public class UserManagementService : IUserManagementService
{    
    private readonly IUserDao userDao ;
    private readonly ILog log;

    public UserManagementService(IUserDao userDao, ILog logger)
    {
       this.userDao = userDao;
       this.log = logger;
    }

    public LoginResponse Login(LoginRequest request)
    {
       // etc
    }  
}


Now the class has no dependencies on concrete implementations and you can mock the interfaces however you feel.  For example, the ILog interface you might want to mock so it logs to the console only.  The IUserDao interface might be mocked to a internal list implementation or you might use a mocking framework such as Moq.