unit Test: How to create a DelegatingHandler to test local API by using Moq in C#?

I want to test some of my local API's. I created a DelegatingHandler to set all the headers that are needed in my production code. but it doesn't work to have a DelegatingHandler for CreateClient in Moq Test to test local Api's. this is my code:

        var appFactory = new WebApplicationFactory<Program>();
        Client = appFactory.CreateClient();

        var cts = new CancellationTokenSource(100000);
        var postData = new TestModel(){Name= "Test"};
        var stringContent = new StringContent(JsonConvert.SerializeObject(postData), Encoding.UTF8, "application/json");

      var response = await Client.PostAsync("/api/register", content, cts.Token);

this is MyDelegatingHandler:

 public class MyDelegatingHandler: DelegatingHandler
{
    private readonly IHttpContextAccessor _httpContextAccessor;

    public MyDelegatingHandler(IHttpContextAccessor httpContextAccessor)
    {
        this._httpContextAccessor = httpContextAccessor;
    }

    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        if (_httpContextAccessor.HttpContext == null) return base.SendAsync(request, cancellationToken);
         if (_httpContextAccessor.HttpContext.Request.Headers["Authorization"].Any())
        {
            var token = _httpContextAccessor.HttpContext.Request.Headers["Authorization"].FirstOrDefault();
            request.Headers.Authorization = new AuthenticationHeaderValue("Bearer",token);
        }

        return base.SendAsync(request, cancellationToken);
    }
}

is there any way to set MyDelegatingHandler for Client to test local API's?