Remove some unused runtime properties and add some tests

test/Velopack.Tests/RuntimeInfoTests.cs

@@ -0,0 +1,43 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Runtime.InteropServices;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Velopack.Tests
+{
+    public class RuntimeInfoTests
+    {
+        [Fact]
+        public void NugetVersionAgreesWithNbgv()
+        {
+            var args = new List<string> { "get-version", "-v", "NuGetPackageVersion" };
+            var current = new ProcessStartInfo("nbgv", args).Output(5000);
+            Assert.Equal(current, VelopackRuntimeInfo.VelopackNugetVersion.ToString());
+        }
+
+        [Fact]
+        public void PlatformIsCorrect()
+        {
+#if NETFRAMEWORK
+            Assert.True(VelopackRuntimeInfo.IsWindows);
+            Assert.Equal(RuntimeOs.Windows, VelopackRuntimeInfo.SystemOs);
+#else
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows)) {
+                Assert.True(VelopackRuntimeInfo.IsWindows);
+                Assert.Equal(RuntimeOs.Windows, VelopackRuntimeInfo.SystemOs);
+            } else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux)) {
+                Assert.True(VelopackRuntimeInfo.IsLinux);
+                Assert.Equal(RuntimeOs.Linux, VelopackRuntimeInfo.SystemOs);
+            } else if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX)) {
+                Assert.True(VelopackRuntimeInfo.IsOSX);
+                Assert.Equal(RuntimeOs.OSX, VelopackRuntimeInfo.SystemOs);
+            } else {
+                throw new PlatformNotSupportedException();
+            }
+#endif
+        }
+    }
+}