How to write unit test for ActionFilter when using Service Locator

I am planning to write an ActionFilter for business validation and in which some services will be resolved via Service Locator(I know this is not good practice and as far as possible i avoid Service Locator pattern, but for this case i want to use it).

OnActionExecuting method of the filter is something like this:

    public override void OnActionExecuting(ActionExecutingContext actionContext)
    {
        // get validator for input;
        var validator = actionContext.HttpContext.RequestServices.GetService<IValidator<TypeOfInput>>();// i will ask another question for this line
        if(!validator.IsValid(input))
        {
            //send errors
        }
    }

Is it possible to write unit test for above ActionFilterand how?