Unit test security of ASP.NET MVC controller methods

Are there any recommended ways to unit test the security of one's MVC controller methods for security (in ASP.NET MVC 5)? e.g. I have administrator users and normal users, and I want to have a unit test to ensure that only administrators can access certain pages. e.g.:

    /// <summary>
    /// Initial page for creating a new <see cref="Widget"/>.
    /// </summary>
    /// <returns>
    /// An <see cref="ActionResult"/> used to indicate the view to be
    /// rendered. Guaranteed not to be null or empty.
    /// </returns>
    [HttpGet]
    [Authorize(Roles = "ADMIN")]
    public ActionResult Create()
    {
        return this.View(new CreateWidgetModel());
    }

... and the unit test should be something like:

    [TestMethod]
    public void VerifyOnlyAdminsCanCreateWidgets()
    {
        Assert.???
    }