How to unit test AntiforgeryToken filter for web api 2

I am trying to write unit test case using mstest for custom filter which has the logic to validate the Antiforgerytoken for POST method in ASP.NET WEB API 2 project.

[AttributeUsage(AttributeTargets.Method, Inherited = true)]
    public class ValidateJsonAntiForgeryTokenAttribute : ActionFilterAttribute
    {
        /// <summary>
        /// Filter the validate the antiforgery token
        /// </summary>
        /// <param name="actionContext"></param>
        public override void OnActionExecuting(HttpActionContext actionContext)
        {
            try
            {
                #region AntiForgeryValidation

                string cookieToken = null;
                string formToken = null;

                if (actionContext.Request.IsAjaxRequest())
                {
                    IEnumerable<string> tokenHeaders;
                    if (actionContext.Request.Headers.TryGetValues("__RequestVerificationToken", out tokenHeaders))
                    {
                        string[] tokens = tokenHeaders.First().Split(':');
                        if (tokens.Length == 2)
                        {
                            cookieToken = tokens[0].Trim();
                            formToken = tokens[1].Trim();
                        }
                    }
                    if (cookieToken != null && formToken !=null)
                    {
                        AntiForgery.Validate(cookieToken, formToken);
                    }
                    else
                    {
                        AntiForgery.Validate();
                    }                    
                }

                #endregion
            }
            catch (Exception ex)
            {
                ErrorSignal.FromCurrentContext().Raise(ex);
                actionContext.Response = actionContext.Request.CreateResponse(HttpStatusCode.Forbidden);
            }            
        }
    }

In the below code IsAjaxRequest is an extension method

public static class HttpRequestMessageExtensions
    {
        public static bool IsAjaxRequest(this HttpRequestMessage request)
        {
            IEnumerable<string> headers;
            if (request.Headers.TryGetValues("X-Requested-With", out headers))
            {
                var header = headers.FirstOrDefault();
                if (!string.IsNullOrWhiteSpace(header))
                {
                    return header.ToLowerInvariant() == "xmlhttprequest";
                }
            }

            return false;
        }
    }

Here my issue how to mock the IsAjaxRequest and how to pass actionContext parameter to the OnActionExecuting method.

Can anyone help me to provide some code samples regarding this?