如何为后台服务编写单元测试？ [英] How can i write unit test for my background service?

问题描述

我正在使用.NET Core（而不是WebHost！）中的HostBuilder。

I'm working with the HostBuilder in .NET Core (not the WebHost !).

我在应用程序中运行了一个托管服务，该服务将覆盖ExecuteAsync /后台服务的StopAsync方法，我想对其进行单元测试。

I have one Hosted Service running in my application that override the ExecuteAsync/StopAsync Method of the background Service and I want to unit test it.

这是我的HostedService：

Here is my HostedService:

    public class DeviceToCloudMessageHostedService : BackgroundService
    {
        private readonly IDeviceToCloudMessageService _deviceToCloudMessageService;
        private readonly AppConfig _appConfig;

        public DeviceToCloudMessageHostedService(IDeviceToCloudMessageService deviceToCloudMessageService, IOptionsMonitor<AppConfig> appConfig)
        {
            _deviceToCloudMessageService = deviceToCloudMessageService;
            _appConfig = appConfig.CurrentValue;
        }

        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            while (!stoppingToken.IsCancellationRequested)
            {
                await _deviceToCloudMessageService.DoStuff(stoppingToken);
                await Task.Delay(_appConfig.Parameter1, stoppingToken);
            }
        }

        public override Task StopAsync(CancellationToken cancellationToken)
        {
            Log.Information("Task Cancelled");
            _deviceToCloudMessageService.EndStuff();
            return base.StopAsync(cancellationToken);
        }

我已经找到了此帖子托管服务.Net-Core的集成测试`
但这是针对QueuedBackgroundService的解释，我没有真的知道我是否可以用相同的方式测试我的。

I already found this post Integration Test For Hosted Service .Net-Core` But it's explained for a QueuedBackgroundService and i don't really know if i can test mine the same way.

我只想知道我的代码是否已执行。我不希望有任何具体结果。
您是否知道如何测试？
非常感谢。

I just want to know if my code is executed. I don't want any specific result. Do you have any idea of how I can test it ? Thanks a lot.

推荐答案

您仍然应该能够采用与链接答案相似的格式。

You should still be able to follow a similar format as the linked answer.

模拟依赖项并注入它们，调用被测方法并声明预期的行为。

Mock the dependencies and inject them, invoke the methods under test and assert the expected behavior.

以下使用Moq来模拟依赖项，并使用 ServiceCollection 来完成注入依赖项的工作。

The following uses Moq to mock the dependencies along with ServiceCollection to do the heavy lifting of injecting the dependencies.

[TestMethod]
public async Task DeviceToCloudMessageHostedService_Should_DoStuff() {
    //Arrange
    IServiceCollection services = new ServiceCollection();
    services.AddSingleton<IHostedService, DeviceToCloudMessageHostedService>();
    //mock the dependencies for injection
    services.AddSingleton(Mock.Of<IDeviceToCloudMessageService>(_ =>
        _.DoStuff(It.IsAny<CancellationToken>()) == Task.CompletedTask
    ));
    services.AddSingleton(Mock.Of<IOptionsMonitor<AppConfig>>(_ =>
        _.CurrentValue == Mock.Of<AppConfig>(c => 
            c.Parameter1 == TimeSpan.FromMilliseconds(1000)
        )
    ));
    var serviceProvider = services.BuildServiceProvider();
    var hostedService = serviceProvider.GetService<IHostedService>();

    //Act
    await hostedService.StartAsync(CancellationToken.None);
    await Task.Delay(1000);//Give some time to invoke the methods under test
    await hostedService.StopAsync(CancellationToken.None);

    //Assert
    var deviceToCloudMessageService = serviceProvider
        .GetRequiredService<IDeviceToCloudMessageService>();
    //extracting mock to do verifications
    var mock = Mock.Get(deviceToCloudMessageService);
    //assert expected behavior
    mock.Verify(_ => _.DoStuff(It.IsAny<CancellationToken>()), Times.AtLeastOnce);
    mock.Verify(_ => _.EndStuff(), Times.AtLeastOnce());
}

现在，理想情况下，这将被视为测试框架代码，因为您基本上是在测试 BackgroundService 在运行时的行为符合预期，但应充分说明如何单独测试这种服务

Now, ideally this would count as testing framework code since you are basically testing that a BackgroundService behaves as expected when run, but it should demonstrate enough about how one would test such a service in isolation

这篇关于如何为后台服务编写单元测试？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！