c# - 使用 2 个后台服务进行集成测试

Question

我有一个 dot net core 项目，我正在尝试在我的两个BackgroundServices.

以下是我目前的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 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));
}

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

为该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商，并会按他们的类型获得服务：

var serviceProvider = services.BuildServiceProvider();

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

或者我会创建可以像这样使用的接口：

public interface IFileWatcherService : IHostedService
{
   ...
}

public interface IFailedTradesWorker : IHostedService
{
   ...
}

services.AddHostedService<IFileWatcherService, FileWatcherService>();
services.AddHostedService<IFailedTradesWorker, FailedTradesWorker>();

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