Resharper 测试运行程序不输出 Console.WriteLine()？

Question

为什么Console.Writeline()从控制台应用程序main()方法执行时会起作用；但是当我使用 resharpers 测试运行器执行相同的操作时，我Console.Writeline()在测试运行器输出窗口中没有看到？

解释这一点的最好方法是举一个例子。

我正在使用：Resharper Ultimate 2017.1.3、Visual Studio 2017 Community 和 .Net 4.6.1 框架。语言是 C#。我还安装了（通过 nuget）nunit 框架 2.6.4。

首先创建一个类库并将以下内容复制粘贴到 .cs 文件中。

using System;
using System.Collections;
using System.Threading;
using NUnit.Framework;

namespace ObserverPatternExample
{
    [TestFixture]
    internal class ObserverTestFixture
    {
        [Test]
        public void DemonstrateObserverPattern()
        {
            var subject = new Subject();
            var a = new Observer(subject, "a");
            var b = new Observer(subject, "b"); // etc. as many observers as you want.

            subject.Go();
        }
    }

    // "subject" is observer pattern lingo. The "subject" will do the broadcasting to the observers.
    public class Subject 
    {
        public delegate void CallbackHandler(string s);
        public event CallbackHandler NotifyEvent;
        private const int waitTimeInMilliseconds = 200;
        private readonly Simulator simulator = new Simulator();
        public string FakeSimulatorState { get; set; }

        public void Go()
        {
            new Thread(Run).Start(); // a good thing to notice: events cross thread boundaries!!!
        }

        private void Run()
        {
            foreach (string s in simulator)
            {
                Console.WriteLine("Subject: " + s);
                FakeSimulatorState = s;
                NotifyEvent?.Invoke(s);
                Thread.Sleep(
                    waitTimeInMilliseconds); // we do this to "pretend" that the simulator is actually doing someting.
            }
        }


    }

    public class Observer : IObserverPattern // the "observer" will subscribe to the event being broadcast by the "subject"
    {
        private readonly string _name;
        public Observer(Subject subject, string name)
        {
            _name = name;
            subject.NotifyEvent += Update;
        }
        public void Update(string state)
        {
            Console.WriteLine("Observer {0}: {1}", _name, state);
        }
    }

    internal interface IObserverPattern
    {
        void Update(string state);
    }

    public class Simulator : IEnumerable
    {
        private readonly string[] _stateSequence = { "BEGIN", "CRAWL", "WALK", "JUMP", "END" };

        public IEnumerator GetEnumerator()
        {
            foreach (var s in _stateSequence)
                yield return s;
        }
    }
}

现在执行测试。我希望在 Resharper 测试运行器输出窗口中看到 Console.WriteLine() 调用显示字符串。但我没有。例如这里是一个截图：

现在让我们执行完全相同的序列，但这次我们将从新的控制台项目 main() 方法调用客户端代码。要进行设置，请复制粘贴以下代码并引用您在上述步骤中创建的类库。

using ObserverPatternExample;

namespace ConsoleApp1
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            var subject = new Subject();
            var a = new Observer(subject, "a");
            var b = new Observer(subject, "b"); // etc. as many observers as you want.

            subject.Go();
        }
    }
}

接下来执行控制台应用程序。您应该看到以下显示：

谁能解释我如何配置我的代码或测试运行器以在测试运行器输出窗口中显示输出？

* 更新 * 我取得了部分成功。InBetween 建议使用 aTraceListener使我意识到我应该使用ConsoleTraceListener. 为了方便起见，我修改了单元测试以显示如下：

using System.Threading;
using NUnit.Framework;

namespace ObserverPatternExample.DontUse
{
    [TestFixture]
    internal class ObserverTestFixture
    {
        [SetUp]
        public void Setup()
        {
            Trace.Listeners.Add(new ConsoleTraceListener());
        }

        [TearDown]
        public void TearDown()
        {
            Trace.Flush();
        }

        [Test]
        public void DemonstrateObserverPattern()
        {
            var subject = new Subject();
            var a = new Observer(subject, "a");
            var b = new Observer(subject, "b"); // etc. as many observers as you want.

            subject.Go();
        }
    }

结果令人惊讶：我确实得到了一些输出；但只有初始 BEGIN 状态。看起来像这样：

小故事：我仍在寻找解决方案。

*** 解决方案 ****

        [Test]
        public void DemonstrateObserverPattern()
        {
            var subject = new Subject();
            var a = new Observer(subject, "a");
            var b = new Observer(subject, "b"); // etc. as many observers as you want.

            subject.Go();

Thread.Sleep(1000); // <--- add this to force test runner to wait for other thread to complete.
        }

Answer 1

看起来 Resharper 正在您的线程完成之前完成。您致电

Thread(Run).Start();

是非阻塞的。这意味着测试线程将在 Go 线程完成之前完成，因此您不会得到任何结果。

请参阅https://msdn.microsoft.com/en-us/library/6x4c42hc(v=vs.110).aspx，其中指出“请注意，对 Start 的调用不会阻止调用线程。”