A Reworked MVC Preview 5 AccountController

[HandleError]
[OutputCache(Location = OutputCacheLocation.None)]
public class AccountController : Controller
{
    public AccountController()
        : this(null, null)
    {
    }

    public AccountController(IFormsAuthentication formsAuth, MembershipProvider provider)
    {
        FormsAuth = formsAuth ?? new FormsAuthenticationWrapper();
        Provider = provider ?? Membership.Provider;
    }

    public IFormsAuthentication FormsAuth
    {
        get;
        private set;
    }

    public MembershipProvider Provider
    {
        get;
        private set;
    }

    [Authorize]
    [AcceptVerbs("GET")]
    public ActionResult ChangePassword()
    {
        ViewData["Title"] = "Change Password";
        ViewData["PasswordLength"] = Provider.MinRequiredPasswordLength;

        return View();
    }

    [Authorize]
    [AcceptVerbs("POST")]
    public ActionResult ChangePassword(string currentPassword, string newPassword, string confirmPassword)
    {
        // Basic parameter validation
        if (String.IsNullOrEmpty(currentPassword))
        {
            ViewData.ModelState.AddModelError("currentPassword", currentPassword, "You must specify a current password.");
        }
        if (newPassword == null || newPassword.Length < Provider.MinRequiredPasswordLength)
        {
            ViewData.ModelState.AddModelError("newPassword", newPassword, String.Format(CultureInfo.InvariantCulture,
                     "You must specify a new password of {0} or more characters.",
                     Provider.MinRequiredPasswordLength));
        }
        if (!String.Equals(newPassword, confirmPassword, StringComparison.Ordinal))
        {
            ViewData.ModelState.AddModelError("newPassword", newPassword, "The new password and confirmation password do not match.");
        }

        if (ViewData.ModelState.IsValid)
        {
            // Attempt to change password
            MembershipUser currentUser = Provider.GetUser(User.Identity.Name, true /* userIsOnline */);
            bool changeSuccessful = false;
            try
            {
                changeSuccessful = currentUser.ChangePassword(currentPassword, newPassword);
            }
            catch
            {
                // An exception is thrown if the new password does not meet the provider's requirements
            }

            if (changeSuccessful)
            {
                return RedirectToAction("ChangePasswordSuccess");
            }
            else
            {
                ViewData.ModelState.AddModelError("password", currentPassword, "The current password is incorrect or the new password is invalid.");
            }
        }

        // If we got this far, something failed, redisplay form
        ViewData["Title"] = "Change Password";
        ViewData["PasswordLength"] = Provider.MinRequiredPasswordLength;

        return View();
    }

    public ActionResult ChangePasswordSuccess()
    {
        ViewData["Title"] = "Change Password";

        return View();
    }

    [AcceptVerbs("GET")]
    public ActionResult Login()
    {
        ViewData["Title"] = "Login";
        ViewData["CurrentPage"] = "login";

        return View();
    }

    [AcceptVerbs("POST")]
    public ActionResult Login(string username, string password, bool? rememberMe)
    {
        // Basic parameter validation
        if (String.IsNullOrEmpty(username))
        {
            ViewData.ModelState.AddModelError("username", username, "You must specify a username.");
        }

        if (ViewData.ModelState.IsValid)
        {
            // Attempt to login
            bool loginSuccessful = Provider.ValidateUser(username, password);

            if (loginSuccessful)
            {
                FormsAuth.SetAuthCookie(username, rememberMe ?? false);
                return RedirectToAction("Index", "Home");
            }
            else
            {
                ViewData.ModelState.AddModelError("*", username, "The username or password provided is incorrect.");
            }
        }

        // If we got this far, something failed, redisplay form
        ViewData["Title"] = "Login";
        ViewData["CurrentPage"] = "login";
        ViewData["username"] = username;

        return View();
    }

    public ActionResult Logout()
    {
        FormsAuth.SignOut();
        return RedirectToAction("Index", "Home");
    }

    protected override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        if (filterContext.HttpContext.User.Identity is WindowsIdentity)
        {
            throw new InvalidOperationException("Windows authentication is not supported.");
        }
    }

    [AcceptVerbs("GET")]
    public ActionResult Register()
    {
        ViewData["Title"] = "Register";
        ViewData["PasswordLength"] = Provider.MinRequiredPasswordLength;

        return View();
    }

    [AcceptVerbs("POST")]
    public ActionResult Register(string username, string email, string password, string confirmPassword)
    {
        // Basic parameter validation
        if (String.IsNullOrEmpty(username))
        {
            ViewData.ModelState.AddModelError("username", username, "You must specify a username.");
        }

        if (String.IsNullOrEmpty(email))
        {
            ViewData.ModelState.AddModelError("email", email, "You must specify an email address.");
        }

        if (password == null || password.Length < Provider.MinRequiredPasswordLength)
        {
            ViewData.ModelState.AddModelError("password", password, String.Format(CultureInfo.InvariantCulture,
                     "You must specify a password of {0} or more characters.",
                     Provider.MinRequiredPasswordLength));
        }

        if (!String.Equals(password, confirmPassword, StringComparison.Ordinal))
        {
            ViewData.ModelState.AddModelError("confirmPassword", confirmPassword, "The password and confirmation do not match.");
        }

        if (ViewData.ModelState.IsValid)
        {

            // Attempt to register the user
            MembershipCreateStatus createStatus;
            MembershipUser newUser = Provider.CreateUser(username, password, email, null, null, true, null, out createStatus);

            if (newUser != null)
            {
                FormsAuth.SetAuthCookie(username, false /* createPersistentCookie */);
                return RedirectToAction("Index", "Home");
            }
            else
            {
                ViewData.ModelState.AddModelError("*", username, ErrorCodeToString(createStatus));
            }
        }

        // If we got this far, something failed, redisplay form
        ViewData["Title"] = "Register";
        ViewData["PasswordLength"] = Provider.MinRequiredPasswordLength;
        ViewData["username"] = username;
        ViewData["email"] = email;

        return View();
    }

    public static string ErrorCodeToString(MembershipCreateStatus createStatus)
    {
        // See http://msdn.microsoft.com/en-us/library/system.web.security.membershipcreatestatus.aspx for
        // a full list of status codes.
        switch (createStatus)
        {
            case MembershipCreateStatus.DuplicateUserName:
                return "Username already exists. Please enter a different user name.";

            case MembershipCreateStatus.DuplicateEmail:
                return "A username for that e-mail address already exists. Please enter a different e-mail address.";

            case MembershipCreateStatus.InvalidPassword:
                return "The password provided is invalid. Please enter a valid password value.";

            case MembershipCreateStatus.InvalidEmail:
                return "The e-mail address provided is invalid. Please check the value and try again.";

            case MembershipCreateStatus.InvalidAnswer:
                return "The password retrieval answer provided is invalid. Please check the value and try again.";

            case MembershipCreateStatus.InvalidQuestion:
                return "The password retrieval question provided is invalid. Please check the value and try again.";

            case MembershipCreateStatus.InvalidUserName:
                return "The user name provided is invalid. Please check the value and try again.";

            case MembershipCreateStatus.ProviderError:
                return "The authentication provider returned an error. Please verify your entry and try again. If the problem persists, please contact your system administrator.";

            case MembershipCreateStatus.UserRejected:
                return "The user creation request has been canceled. Please verify your entry and try again. If the problem persists, please contact your system administrator.";

            default:
                return "An unknown error occurred. Please verify your entry and try again. If the problem persists, please contact your system administrator.";
        }
    }
}

// The FormsAuthentication type is sealed and contains static members, so it is difficult to
// unit test code that calls its members. The interface and helper class below demonstrate
// how to create an abstract wrapper around such a type in order to make the AccountController
// code unit testable.

public interface IFormsAuthentication
{
    void SetAuthCookie(string userName, bool createPersistentCookie);
    void SignOut();
}

public class FormsAuthenticationWrapper : IFormsAuthentication
{
    public void SetAuthCookie(string userName, bool createPersistentCookie)
    {
        FormsAuthentication.SetAuthCookie(userName, createPersistentCookie);
    }
    public void SignOut()
    {
        FormsAuthentication.SignOut();
    }
}

<%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" AutoEventWireup="true" CodeBehind="Login.aspx.cs" Inherits="GuildSite.Views.Account.Login" %>

<asp:Content ID="loginContent" ContentPlaceHolderID="MainContent" runat="server">
    <h2>Login</h2>
    
    <p>
        Please enter your username and password below. If you don't have an account,
        please <%= Html.ActionLink("register", "Register") %>.
    </p>
    
    <%= Html.ValidationSummary()%>
             
    <form method="post" action="<%= Html.AttributeEncode(Url.Action("Login")) %>">
        <div class="form">
            <table>
                <tr>
                    <td>Username:</td>
                    <td><%= Html.TextBox("username") %></td>
                </tr>
                <tr>
                    <td>Password:</td>
                    <td><%= Html.Password("password") %></td>
                </tr>
                <tr>
                    <td></td>
                    <td><input type="checkbox" name="rememberMe" value="true" /> Remember me?</td>
                </tr>
                <tr>
                    <td></td>
                    <td><input type="submit" value="Login" /></td>
                </tr>
            </table>
        </div>
    </form>
</asp:Content>

<%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" AutoEventWireup="true" CodeBehind="Register.aspx.cs" Inherits="GuildSite.Views.Account.Register" %>

<asp:Content ID="registerContent" ContentPlaceHolderID="MainContent" runat="server">
    <h2>Account Creation</h2>
    
    <p>
        Use the form below to create a new account. 
    </p>
    <p>
        Passwords are required to be a minimum of <%=Html.Encode(ViewData["PasswordLength"])%> characters in length.
    </p>

    <%= Html.ValidationSummary()%>

    <form method="post" action="<%= Html.AttributeEncode(Url.Action("Register")) %>">
        <div class="form">
            <table>
                <tr>
                    <td>Username:</td>
                    <td><%= Html.TextBox("username") %></td>
                </tr>
                <tr>
                    <td>Email:</td>
                    <td><%= Html.TextBox("email") %></td>
                </tr>
                <tr>
                    <td>Password:</td>
                    <td><%= Html.Password("password") %></td>
                </tr>
                <tr>
                    <td>Confirm password:</td>
                    <td><%= Html.Password("confirmPassword") %></td>
                </tr>
                <tr>
                    <td></td>
                    <td><input type="submit" value="Register" /></td>
                </tr>
            </table>
        </div>
    </form>
</asp:Content>