Fix and re-enable build3 tests.

test/EndToEnd/GivenDotNetUsesMSBuild.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation and contributors. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
+using System.Runtime.InteropServices;
 using Microsoft.DotNet.Tools.Test.Utilities;
 using Xunit;
 
@@ -8,38 +9,43 @@ namespace Microsoft.DotNet.Tests.EndToEnd
 {
     public class GivenDotNetUsesMSBuild : TestBase
     {
-        [Fact(Skip="ResolveNuGetPackageAssets needs to be made case insensitive.")]
+        [Fact]
         public void ItCanNewRestoreBuildRunMSBuildProject()
         {
-            using (DisposableDirectory directory = Temp.CreateDirectory())
+            // The current ResolveNuGetAssets target does not work on case-sensitive file systems.  We need https://github.com/dotnet/sdk/pull/10
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ||
+                RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
             {
-                string projectDirectory = directory.Path;
+                using (DisposableDirectory directory = Temp.CreateDirectory())
+                {
+                    string projectDirectory = directory.Path;
 
-                new NewCommand()
-                    .WithWorkingDirectory(projectDirectory)
-                    .Execute("-t msbuild")
-                    .Should()
-                    .Pass();
+                    new NewCommand()
+                        .WithWorkingDirectory(projectDirectory)
+                        .Execute("-t msbuild")
+                        .Should()
+                        .Pass();
 
-                new RestoreCommand()
-                    .WithWorkingDirectory(projectDirectory)
-                    .Execute()
-                    .Should()
-                    .Pass();
+                    new RestoreCommand()
+                        .WithWorkingDirectory(projectDirectory)
+                        .Execute()
+                        .Should()
+                        .Pass();
 
-                new Build3Command()
-                    .WithWorkingDirectory(projectDirectory)
-                    .Execute()
-                    .Should()
-                    .Pass();
+                    new Build3Command()
+                        .WithWorkingDirectory(projectDirectory)
+                        .Execute()
+                        .Should()
+                        .Pass();
 
-                new Run3Command()
-                    .WithWorkingDirectory(projectDirectory)
-                    .ExecuteWithCapturedOutput()
-                    .Should()
-                    .Pass()
-                    .And
-                    .HaveStdOutContaining("Hello World!");
+                    new Run3Command()
+                        .WithWorkingDirectory(projectDirectory)
+                        .ExecuteWithCapturedOutput()
+                        .Should()
+                        .Pass()
+                        .And
+                        .HaveStdOutContaining("Hello World!");
+                }
             }
         }
     }