Unit Test Relies on UserManager and RoleManager

I am trying to unit test some of my methods that rely on UserManager and RoleManager and am having some difficulty.

Should I mock the UserManager and RoleManager and then pass it to the AdminController? or should I first access the AccountController's default SignIn action and authenticate. I am unsure how to do both options or what the best way to approach this is.

When not authenticating / instantiating the managers I get NullReferenceExceptions on the UserManager

My test

    [Test]
    public void MaxRole_SuperAdmin()
    {
        var adminController = new AdminController();
        var maxRole = adminController.GetMaxRole(SuperAdminUserId);

        Assert.AreEqual(maxRole, "Super Admin");
    }

Controller and Method

[Authorize(Roles = "APGame Admin, APGame Investigator")]
[RequireHttps]
public class AdminController : Controller
{

    private ApplicationUserManager _userManager;

    public ApplicationUserManager UserManager
    {
        get { return _userManager ?? HttpContext.GetOwinContext().GetUserManager<ApplicationUserManager>(); }
        private set { _userManager = value; }
    }

    private ApplicationRoleManager roleManager;

    public ApplicationRoleManager RoleManager
    {
        get
        {
            return roleManager ?? HttpContext.GetOwinContext().Get<ApplicationRoleManager>();
        }
        private set { roleManager = value; }
    }

    public string GetMaxRole(string userId)
    {
        IEnumerable<string> userRoles = UserManager.GetRoles(userId);

        string role = null;

        if (userRoles.Contains("APGame Admin"))
        {
            if (userRoles.Contains("TeVelde Group") && userRoles.Contains("Genomics Group"))
                role = "Super Admin";

            else role = "Admin";
        }

        else if (userRoles.Contains("APGame Investigator"))
        {
            role = "Investigator";
        }

        else if (userRoles.Contains("APGame User"))
        {
            role = "User";
        }

        else
        {
            //TODO: Log no role, HIGH
        }

        return role;
    }
}