ensure RID is passed to test runner by making it an app. Must :fire: later.

Ix.NET/Source/Tests/Program.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace System.Linq
+{
+    public class Program
+    {
+        public static void Main(string[] args)
+        {
+
+        }
+    }
+}

Ix.NET/Source/Tests/project.json

@@ -9,6 +9,9 @@
     "projectUrl": "https://github.com/Reactive-Extensions/Rx.NET",
     "licenseUrl": "https://raw.githubusercontent.com/Reactive-Extensions/Rx.NET/master/Ix.NET/Source/license.txt",
     "requireLicenseAcceptance": true,
+    "compilationOptions": {
+        "emitEntryPoint": true
+    },
     "dependencies": {
         "System.Interactive.Providers": { "target": "project" },
         "System.Interactive.Async.Providers": { "target": "project" },