如何在没有Moq的情况下在C#中实例化FormFile实例？

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Internal;
using System.IO;

public static class FormFileHelper
{
    public static IFormFile CreateFormFile(string filePath, string contentType)
    {
        var fileInfo = new FileInfo(filePath);
        var fileName = fileInfo.Name;

        var stream = new FileStream(filePath, FileMode.Open);
        var formFile = new FormFile(stream, 0, stream.Length, null, fileName)
        {
            Headers = new HeaderDictionary(),
            ContentType = contentType
        };

        return formFile;
    }
}

var filePath = "path/to/file.jpg";
var contentType = "image/jpeg";

var formFile = FormFileHelper.CreateFormFile(filePath, contentType);