单元测试启动多线程并行处理的简单方法

单元测试中经常需要对[ThreadStatic]以及一些互斥环境的处理进行简单验证，启动并行处理方法很多，这里介绍一个简单的方法。

代码

static void Parallel(params ThreadStart[] actions)
{
    List<Thread> threads = actions.Select(a => new Thread(a)).ToList();
    threads.ForEach(t => t.Start());
    threads.ForEach(t => t.Join());
}

下面是一个完整的例子：

代码

using System.Collections.Generic;
using System.Linq;

using System.Threading;
using System.Diagnostics;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace VisionLogic.Training.ParallelUnitTesting
{
    [TestClass]
    public class ObjectWithIdentifierFixture
    {
        [TestMethod]
        public void TestPerThreadExecution()
        {
            Parallel(
                delegate { ThreadInternalA(); },
                delegate { ThreadInternalB(); }
                );
        }

        void ThreadInternalA()
        {
            WriteLine("a1");
            Thread.Sleep(2000);
            WriteLine("a2");
        }

        void ThreadInternalB()
        {
            WriteLine("b1");
            Thread.Sleep(1000);
            WriteLine("b2");
        }

        #region Helper Methods

        static void WriteLine(string message)
        {
            Trace.WriteLine(string.Format("thread {0} : {1}", Thread.CurrentThread.ManagedThreadId, message));
        }

        static void Parallel(params ThreadStart[] actions)
        {
            List<Thread> threads = actions.Select(a => new Thread(a)).ToList();
            threads.ForEach(t => t.Start());
            threads.ForEach(t => t.Join());
        }

        #endregion
    }
}

执行结果可以从Output窗口看到，大致如下：（这里采用TestDriven.NET执行）

------ Test started: Assembly: ParallelUnitTesting.dll ------

thread 13 : a1
thread 14 : b1
thread 14 : b2
thread 13 : a2

1 passed, 0 failed, 0 skipped, took 2.86 seconds (Ad hoc).

注意：这里没有使用 delegate.BeginInvoke 是因为它可能使用线程池，导致并没有实际启动多个线程。