Get free port starting from 8001 instead of using TcpListener.

Enable kestrel tests to run in parallel.

test/Kestrel.Tests/DotnetTest.cs

@@ -12,8 +12,6 @@ using Xunit;
 using System.Threading.Tasks;
 using FluentAssertions;
 
-[assembly: CollectionBehavior(DisableTestParallelization = true)]
-
 namespace Microsoft.DotNet.Kestrel.Tests
 {
     public class DotnetTest : TestBase

test/Microsoft.DotNet.Tools.Tests.Utilities/NetworkUtils/NetworkHelper.cs

@@ -2,11 +2,8 @@ using System;
 using System.Collections.Generic;
 using System.Net;
 using System.Net.Http;
-using System.Net.Sockets;
-using System.Runtime.InteropServices;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.DotNet.ProjectModel;
 using FluentAssertions;
 
 namespace Microsoft.DotNet.Tools.Test.Utilities
@@ -16,8 +13,6 @@ namespace Microsoft.DotNet.Tools.Test.Utilities
         // in milliseconds
         private const int Timeout = 20000;
 
-        private static Queue<TcpListener> s_PortPool = new Queue<TcpListener>();
-
         public static string Localhost { get; } = "http://localhost";
 
         public static bool IsServerUp(string url)
@@ -55,36 +50,9 @@ namespace Microsoft.DotNet.Tools.Test.Utilities
             }
         }
 
-        public static int GetFreePort()
-        {
-            lock (s_PortPool)
-            {
-                if (s_PortPool.Count == 0)
-                {
-                    for (int i = 0; i < 20; i++)
-                    {
-                        var tcpl = new TcpListener(IPAddress.Loopback, 0);
-                        tcpl.Start();
-                        s_PortPool.Enqueue(tcpl);
-                    }
-
-                    Console.WriteLine($"Ports Count >>>>>>>>>>>>>>>>>>> {s_PortPool.Count}");
-                }
-
-                var currentTcpl = s_PortPool.Dequeue();
-                var port = ((IPEndPoint)currentTcpl.LocalEndpoint).Port;
-                currentTcpl.Stop();
-                currentTcpl = null;
-                GC.Collect();
-                GC.WaitForPendingFinalizers();
-
-                return port;
-            }
-        }
-
         public static string GetLocalhostUrlWithFreePort()
         {
-            return $"{Localhost}:{GetFreePort()}/";
+            return $"{Localhost}:{PortManager.GetPort()}/";
         }
     }
 }

test/Microsoft.DotNet.Tools.Tests.Utilities/NetworkUtils/PortManager.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+
+namespace Microsoft.DotNet.Tools.Test.Utilities
+{
+    public static class PortManager
+    {
+        private static int s_nextPort = 8001;
+
+        public static int GetPort()
+        {
+            return Interlocked.Increment(ref s_nextPort);
+        }
+    }
+}

test/Microsoft.DotNet.Tools.Tests.Utilities/project.json

@@ -8,6 +8,7 @@
     "Microsoft.NETCore.App": "1.0.0-rc2-23931",
     "System.Runtime.Serialization.Primitives": "4.1.1-rc2-23931",
     "System.Collections.Immutable": "1.2.0-rc2-23931",
+    "System.Net.NetworkInformation": "4.1.0-rc2-23931",
     "FluentAssertions": "4.0.0",
     "xunit": "2.1.0",
     "dotnet-test-xunit": "1.0.0-dev-128011-22",