How can I write unit test using xunit moq framework for ioperationfilter fileupload

IOperationFilter

<pre>using Microsoft.OpenApi.Models;

using Swashbuckle.AspNetCore.SwaggerGen;

namespace LoanCare.Services.Payment.Api.Filters;

/// <summary>
/// FileUpload Attribute
/// </summary>
[AttributeUsage(AttributeTargets.Method)]
public sealed class FileUploadAttribute : Attribute { }


/// <summary>
/// Filter for IFormFile
/// </summary>
public class FormFileOperationFilter : IOperationFilter
{
    private static readonly string[] FileParameters = { "contentType", "contentDisposition", "headers", "length", "name", "fileName" };
    private const string FormData = "multipart/form-data";
    private const string Json = "application/json";
    /// <summary>
    /// Apply method of IOperationFilter
    /// </summary>
    /// <param name="operation"></param>
    /// <param name="context"></param>
    public void Apply(OpenApiOperation operation, OperationFilterContext context)
    {
        //request argument null check
        if (context is null)
        {
            throw new ArgumentNullException(nameof(context));
        }
        if (operation is null)
        {
            throw new ArgumentNullException(nameof(operation));
        }

        var attr = context.MethodInfo.GetCustomAttributes(true).OfType<FileUploadAttribute>().Any();
        if (!attr)
        {
            return;
        }

        var content = operation.RequestBody.Content;

        var jsonProperties = GetProperties(content, Json);
        foreach (var parameter in jsonProperties.Where(p => FileParameters.Contains(p.Key)))
        {
            jsonProperties.Remove(parameter);
        }
        if (jsonProperties.Count == 0)
        {
            content.Remove(Json);
        }

        var formDataProperties = GetProperties(content, FormData);
        formDataProperties.Add("file", new OpenApiSchema { Type = "file" });
    }

    private static IDictionary<string, OpenApiSchema> GetProperties(IDictionary<string, OpenApiMediaType> contents, string mediaType)
    {
        if (!contents.ContainsKey(mediaType))
        {
            contents.Add(mediaType, new OpenApiMediaType
            {
                Schema = new OpenApiSchema
                {
                    Type = "object",
                    Properties = new Dictionary<string, OpenApiSchema>()
                }
            });
        }
        return contents[mediaType].Schema.Properties;
    }
}