FilterTest.cs

class FilterTest
{
    public FilterTest(Dictionary<Type, object> parameters)
    {
        HttpContext httpContext = new DefaultHttpContext();
        RouteData routeData = new RouteData();
        List<ParameterDescriptor> parameterDescriptors =
            parameters.Select(pair => new ParameterDescriptor
            {
                BindingInfo = new BindingInfo
                {
                    BindingSource = BindingSource.Body
                },
                Name = pair.Key.Name,
                ParameterType = pair.Key
            })
            .ToList();
        ActionDescriptor actionDescriptor = new ActionDescriptor
        {
            Parameters = parameterDescriptors
        };

        ActionContext = new ActionContext(
            httpContext,
            routeData,
            actionDescriptor);
        Filters = new List<IFilterMetadata>();
        ActionArguments = parameters.ToDictionary(pair => pair.Key.Name, pair => pair.Value);

        Controller = new object();
    }

    public ActionContext ActionContext { get; }
    public IList<IFilterMetadata> Filters { get; }
    public IDictionary<string, object> ActionArguments { get; }
    public object Controller { get; }

    public ActionExecutingContext CreateActionExecutingContext()
        => new ActionExecutingContext(ActionContext, Filters, ActionArguments, Controller);

    public ActionExecutedContext CreateActionExecutedContext()
        => new ActionExecutedContext(ActionContext, Filters, Controller);
}