More robust port assignment for tests.

test/Microsoft.AspNetCore.Server.Kestrel.FunctionalTests/PortManager.cs

@@ -7,11 +7,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.FunctionalTests
 {
     public static class PortManager
     {
-        private static int _nextPort = 8001;
-
         public static int GetPort()
         {
-            return Interlocked.Increment(ref _nextPort);
+            return TestCommon.PortManager.GetNextPort();
         }
     }
 }

test/Microsoft.AspNetCore.Server.Kestrel.FunctionalTests/project.json

@@ -4,6 +4,7 @@
     "Microsoft.NETCore.Platforms": "1.0.1-*",
     "Microsoft.AspNetCore.Http.Abstractions": "1.0.0-*",
     "Microsoft.AspNetCore.Server.Kestrel": "1.0.0-*",
+    "Microsoft.AspNetCore.Server.Kestrel.TestCommon": "1.0.0-*",
     "Microsoft.AspNetCore.Testing": "1.0.0-*",
     "xunit": "2.1.0"
   },

test/Microsoft.AspNetCore.Server.Kestrel.TestCommon/PortManager.cs

@@ -0,0 +1,38 @@
+using System.Net;
+using System.Net.Sockets;
+
+namespace Microsoft.AspNetCore.Server.Kestrel.TestCommon
+{
+    public static class PortManager
+    {
+        public static int _nextPort = 8001;
+        public static object _portLock = new object();
+        
+        public static int GetNextPort()
+        {
+            lock (_portLock)
+            {
+                using (var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
+                {
+                    while (true)
+                    {
+                        try
+                        {
+                            var port = _nextPort++;
+                            socket.Bind(new IPEndPoint(IPAddress.Loopback, port));
+                            return port;
+                        }
+                        catch (SocketException)
+                        {
+                            // Retry unless exhausted
+                            if (_nextPort == 65536)
+                            {
+                                throw;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}

test/Microsoft.AspNetCore.Server.Kestrel.TestCommon/project.json

@@ -0,0 +1,18 @@
+{
+  "version": "1.0.0-*",
+  "frameworks": {
+    "net451": { },
+    "netstandard1.3": {
+      "dependencies": {
+        "System.Threading": "4.0.11-*",
+        "System.Net.Sockets": "4.1.0-*"
+      },
+      "imports": [
+        "portable-net45+win8"
+      ]
+    }
+  },
+  "compilationOptions": {
+    "keyFile": "../../tools/Key.snk"
+  }
+}

test/Microsoft.AspNetCore.Server.KestrelTests/TestServer.cs

@@ -6,6 +6,7 @@ using System.Threading;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Server.Kestrel;
 using Microsoft.AspNetCore.Server.Kestrel.Http;
+using Microsoft.AspNetCore.Server.Kestrel.TestCommon;
 
 namespace Microsoft.AspNetCore.Server.KestrelTests
 {
@@ -14,8 +15,6 @@ namespace Microsoft.AspNetCore.Server.KestrelTests
     /// </summary>
     public class TestServer : IDisposable
     {
-        private static int _nextPort = 9001;
-
         private KestrelEngine _engine;
         private IDisposable _server;
         ServerAddress _address;
@@ -62,7 +61,7 @@ namespace Microsoft.AspNetCore.Server.KestrelTests
 
         public static int GetNextPort()
         {
-            return Interlocked.Increment(ref _nextPort);
+            return PortManager.GetNextPort();
         }
     }
 }

test/Microsoft.AspNetCore.Server.KestrelTests/project.json

@@ -4,6 +4,7 @@
     "Microsoft.NETCore.Platforms": "1.0.1-*",
     "Microsoft.AspNetCore.Server.Kestrel": "1.0.0-*",
     "Microsoft.AspNetCore.Server.Kestrel.Https": "1.0.0-*",
+    "Microsoft.AspNetCore.Server.Kestrel.TestCommon": "1.0.0-*",
     "Microsoft.AspNetCore.Testing": "1.0.0-*",
     "xunit": "2.1.0"
   },