Csharp try DI 时出现未定义无参数构造函数错误

我正在try 为依赖项注入注册一个类，但是当我试图通过我的构造函数注入它时，我得到了以下错误:

System.MissingMethodException:‘没有为类型’MauiClient.MainPage‘定义无参数构造函数.’

我在主程序文件中注册服务，如下所示:

MainProgram.cs:

using Accounting.Shared.Services;
using Microsoft.Extensions.Logging;

namespace MauiClient
{
    public static class MauiProgram
    {
        public static MauiApp CreateMauiApp()
        {
            var builder = MauiApp.CreateBuilder();

            builder
                .UseMauiApp<App>()
                .ConfigureFonts(fonts =>
                {
                    fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");
                    fonts.AddFont("OpenSans-Semibold.ttf", "OpenSansSemibold");
                });

            builder.Services.AddTransient<ITestService>(s =>
            {
                var httpClient = new HttpClient();
                var token = "";
                return new TestService(httpClient, token);
            });

            return builder.Build();
        }
    }
}

我的实际服务类: TestService.cs:

namespace Accounting.Shared.Services;

public interface ITestService
{
}

public class TestService : ITestService
{
    private HttpClient _httpClient;
    private string _token;

    public TestService(HttpClient httpClient, string token)
    {        
        _httpClient = httpClient;
        _token = token;
    }
}

最后，在MainPage.xaml.cs中，我try 依赖项注入:

namespace MauiClient;

using Accounting.Shared.Services;

public partial class MainPage : ContentPage
{
    int count = 0;

    private ITestService _testService;

    public MainPage(ITestService testService)
    {
        InitializeComponent();
        _testService = testService; 
    }

    private void OnCounterClicked(object sender, EventArgs e)
    {
    }
}

我不明白为什么它不能将其作为参数传递.任何帮助都将不胜感激.