托管服务.Net-Core的集成测试 [英] Integration Test For Hosted Service .Net-Core`

问题描述

我有一个要测试的QueueTask托管服务(.Net-Core的新后台服务).我的queuedHosted服务看起来像这样:

I have a QueueTask Hosted service (.Net-Core's new background service) that I'd like to test. My queuedHosted service looks like so:

public QueuedHostedService(IServiceProvider serviceProvider, IBackgroundTaskQueue taskQueue, ILoggerFactory loggerFactory)
{
    TaskQueue = taskQueue;
    _logger = loggerFactory.CreateLogger<QueuedHostedService>();
    _serviceProvider = serviceProvider;
}

protected async override Task ExecuteAsync(CancellationToken stoppingToken)
{
    using (var scope = _serviceProvider.CreateScope())
    {
        while (false == stoppingToken.IsCancellationRequested)
        {
            var workItem = await TaskQueue.DequeueAsync(stoppingToken);
            try
            {
                await workItem(scope.ServiceProvider, stoppingToken);
            }
            catch (Exception ex)
            {
                this._logger.LogError(ex, $"Error occurred executing {nameof(workItem)}.");
            }
        }
    }
}

它只是从队列中读取任务，并在传入任务时执行它们.我已经验证了托管服务正在生产中.我为它写了一个测试，如下所示:

It just reads tasks from the queue and executes them as they come in. I've already verified that the Hosted Service is working in Production. I wrote a test for it like so:

[TestMethod]
public async Task Verify_Hosted_Service_Executes_Task()
{
    IServiceCollection services = new ServiceCollection();
    services.AddSingleton<ILoggerFactory, NullLoggerFactory>();
    services.AddHostedService<QueuedHostedService>();
    services.AddSingleton<IBackgroundTaskQueue, BackgroundTaskQueue>();
    var serviceProvider = services.BuildServiceProvider();

    var backgroundQueue = serviceProvider.GetService<IBackgroundTaskQueue>();

    var isExecuted = false;
    backgroundQueue.QueueBackgroundWorkItem(async (sp, ct) => {
        isExecuted = true;
    });

    await Task.Delay(10000);
    Assert.IsTrue(isExecuted);
}

但是，我的回叫从未被打过.如何让我的任务在后台服务上执行?

However, my call back is never hit. How can I get my task to executue on the Background Service?

修改

我模仿的是创业公司，假设后台服务可以正常工作， 但显然我的服务从未启动，

I was mimicking the startup, and assumed by background service would just work, but apparently my service is never started,

如何从.Net-Core开始规范托管服务?

How is the Hosted Service normalled Started from .Net-Core?

推荐答案

托管服务是框架启动的，是WebHost启动过程的一部分

Hosted services are started by the framework as part of the WebHost's start process

// Fire IHostedService.Start
await _hostedServiceExecutor.StartAsync(cancellationToken).ConfigureAwait(false);

源

收集所有已注册的IHostedService，枚举并依次启动

via the HostedServiceExecutor which would take a collection of all the registered IHostedService, enumerate them and start them in turn

public HostedServiceExecutor(ILogger<HostedServiceExecutor> logger, IEnumerable<IHostedService> services)
{
    _logger = logger;
    _services = services;
}

public async Task StartAsync(CancellationToken token)
{
    try
    {
        await ExecuteAsync(service => service.StartAsync(token));
    }
    catch (Exception ex)
    {
        _logger.ApplicationError(LoggerEventIds.HostedServiceStartException, "An error occurred starting the application", ex);
    }
}

来源

但是，由于您要单独测试托管服务，因此您必须充当框架并自己启动服务.

But since you are testing the hosted service on its own, you have to act as the framework and start the service yourself.

[TestMethod]
public async Task Verify_Hosted_Service_Executes_Task() {
    IServiceCollection services = new ServiceCollection();
    services.AddSingleton<ILoggerFactory, NullLoggerFactory>();
    services.AddHostedService<QueuedHostedService>();
    services.AddSingleton<IBackgroundTaskQueue, BackgroundTaskQueue>();
    var serviceProvider = services.BuildServiceProvider();

    var service = serviceProvider.GetService<IHostedService>() as QueuedHostedService;

    var backgroundQueue = serviceProvider.GetService<IBackgroundTaskQueue>();

    await service.StartAsync(CancellationToken.None);

    var isExecuted = false;
    backgroundQueue.QueueBackgroundWorkItem(async (sp, ct) => {
        isExecuted = true;
    });

    await Task.Delay(10000);
    Assert.IsTrue(isExecuted);

    await service.StopAsync(CancellationToken.None);
}

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