具有2个后台服务的集成测试

Question

我有一个点网核心项目，试图在我的两个BackgroundServices之间编写集成测试。

下面是我当前的xUnit测试：

[Fact]
public async Task FileWatcherIntegration()
{
    IServiceCollection services = new ServiceCollection();
    services.AddHostedService<FileWatcherService>();
    services.AddHostedService<FailedTradesWorker>();
    services.AddSingleton(fileWatcherOptions);
    services.AddSingleton<ILogger<FileWatcherService>>(logger);

    var serviceProvider = services.BuildServiceProvider();
    var tradeServiceProdiver = tradeServices.BuildServiceProvider();

    var fileWatcher = serviceProvider.GetService<IHostedService>() as FileWatcherService; 
    var tradeWorker = serviceProvider.GetService<IHostedService>() as FailedTradesWorker;

    // act
    await tradeWorker.StartAsync(CancellationToken.None);
    await fileWatcher.StartAsync(CancellationToken.None);

    /* Ommited */


    await tradeWorker.StopAsync(CancellationToken.None);
    await fileWatcher.StopAsync(CancellationToken.None);

    // assert
    Assert.True(File.Exists(fileWatcherOptions.DestinationPathAndName));
}

我的测试在行var fileWatcher = serviceProvider.GetService<IHostedService>() as FileWatcherService;上失败，并显示错误消息：Unable to resolve service for type

为此测试设置我的服务的正确方法是什么？

Answer 1

这看起来很奇怪：

var serviceProvider = services.BuildServiceProvider();
var tradeServiceProdiver = tradeServices.BuildServiceProvider();

var fileWatcher = serviceProvider.GetService<IHostedService>() as FileWatcherService; 
var tradeWorker = serviceProvider.GetService<IHostedService>() as FailedTradesWorker;

我会使用一个服务提供者，并且会按其类型获得服务：

var serviceProvider = services.BuildServiceProvider();

var fileWatcher = serviceProvider.GetService<FileWatcherService>();
var tradeWorker = serviceProvider.GetService<FailedTradesWorker>();