unittestingiformfiletwo.cs

public class ImageService : IImageService
{
    public async Task<string> SaveImage(int userId, IFormFile uploadedImage)
    {
        // convert IFormFile to Image and validate
        using (var image = Image.FromStream(uploadedImage.OpenReadStream()))
        {
            if (image.Width > 640 || image.Height > 480)
            {
                // do some resizing and then save image
            }
            else
            {
                // save original image for user
            }
        }

        return "image saved";
    }
}