Fix and re-enable build3 tests.

build/Microsoft.DotNet.Cli.Compile.targets

@@ -136,6 +136,10 @@
       <Copy SourceFiles="$(SdkOutputDirectory)/%(FilesToMove.Identity)"
             DestinationFiles="$(SdkOutputDirectory)/%(FilesToMove.Filename).dll" />
 
+      <!-- MSBuild needs csc.exe to be in the SdkOutputDirectory, or else it can't invoke it -->
+      <Move SourceFiles="$(BinaryToCorehostifyOutDir)/csc.exe"
+            DestinationFiles="$(SdkOutputDirectory)/csc.exe" />
+
       <Copy SourceFiles="$(SdkOutputDirectory)/redist.deps.json"
             DestinationFiles="$(SdkOutputDirectory)/%(BundledTools.Identity).deps.json" />
 

build/test/TestProjects.targets

@@ -58,7 +58,9 @@
 
       <PreTestProjectsToExclude Include="test$(PathSeparator)**$(PathSeparator)bin$(PathSeparator)**$(PathSeparator)project.json" />
 
-      <PreTestProjectsToExclude Include="test$(PathSeparator)dotnet-build3.Tests$(PathSeparator)project.json" />
+      <!-- The current ResolveNuGetAssets target does not work on case-sensitive file systems.  We need https://github.com/dotnet/sdk/pull/10 -->
+      <PreTestProjectsToExclude Condition="'$(OSName)' != 'win' and '$(OSName)' != 'osx'"
+                                Include="test$(PathSeparator)dotnet-build3.Tests$(PathSeparator)project.json" />
 
       <TestProjectsToExclude Include="%(PreTestProjectsToExclude.RelativeDir)project.json" />
 

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;
 
@@ -8,8 +9,12 @@ namespace Microsoft.DotNet.Tests.EndToEnd
 {
     public class GivenDotNetUsesMSBuild : TestBase
     {
-        [Fact(Skip="ResolveNuGetPackageAssets needs to be made case insensitive.")]
+        [Fact]
         public void ItCanNewRestoreBuildRunMSBuildProject()
+        {
+            // 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))
             {
                 using (DisposableDirectory directory = Temp.CreateDirectory())
                 {
@@ -43,4 +48,5 @@ namespace Microsoft.DotNet.Tests.EndToEnd
                 }
             }
         }
+    }
 }