Added some utilities that will be helpful for testing (#7321)

Author: TIHan

eng/Build.ps1

@@ -277,6 +277,25 @@ function Prepare-TempDir() {
     Copy-Item (Join-Path $RepoRoot "tests\Resources\Directory.Build.targets") $TempDir
 }
 
+function EnablePreviewSdks() {
+  if (Test-Path variable:global:_MSBuildExe) {
+    return
+  }
+  $vsInfo = LocateVisualStudio
+  if ($vsInfo -eq $null) {
+    # Preview SDKs are allowed when no Visual Studio instance is installed
+    return
+  }
+
+  $vsId = $vsInfo.instanceId
+  $vsMajorVersion = $vsInfo.installationVersion.Split('.')[0]
+
+  $instanceDir = Join-Path ${env:USERPROFILE} "AppData\Local\Microsoft\VisualStudio\$vsMajorVersion.0_$vsId"
+  Create-Directory $instanceDir
+  $sdkFile = Join-Path $instanceDir "sdk.txt"
+  'UsePreviews=True' | Set-Content $sdkFile
+}
+
 try {
     Process-Arguments
 
@@ -288,6 +307,7 @@ try {
 
     if ($ci) {
         Prepare-TempDir
+        EnablePreviewSdks
 
         # enable us to build netcoreapp2.1 binaries
         $global:_DotNetInstallDir = Join-Path $RepoRoot ".dotnet"

eng/Versions.props

@@ -100,6 +100,8 @@
     <MicrosoftCodeAnalysisEditorFeaturesWpfVersion>$(RoslynVersion)</MicrosoftCodeAnalysisEditorFeaturesWpfVersion>
     <MicrosoftCodeAnalysisExternalAccessFSharpVersion>$(RoslynVersion)</MicrosoftCodeAnalysisExternalAccessFSharpVersion>
     <MicrosoftCodeAnalysisWorkspacesCommonVersion>$(RoslynVersion)</MicrosoftCodeAnalysisWorkspacesCommonVersion>
+    <MicrosoftCodeAnalysisCSharpVersion>$(RoslynVersion)</MicrosoftCodeAnalysisCSharpVersion>
+    <MicrosoftCodeAnalysisTestResourcesProprietaryVersion>2.0.17</MicrosoftCodeAnalysisTestResourcesProprietaryVersion>
     <MicrosoftVisualStudioLanguageServicesVersion>$(RoslynVersion)</MicrosoftVisualStudioLanguageServicesVersion>
     <!-- Microsoft Build packages -->
     <MicrosoftBuildOverallPackagesVersion>16.0.461</MicrosoftBuildOverallPackagesVersion>
@@ -166,7 +168,8 @@
     <MicrosoftCompositionVersion>1.0.30</MicrosoftCompositionVersion>
     <MicrosoftMSXMLVersion>8.0.0-alpha</MicrosoftMSXMLVersion>
     <MicrosoftNetCompilersVersion>2.7.0</MicrosoftNetCompilersVersion>
-    <MicrosoftNETCoreILDAsmVersion>2.0.3</MicrosoftNETCoreILDAsmVersion>
+    <MicrosoftNETCoreILDAsmVersion>3.0.0-preview-27318-01</MicrosoftNETCoreILDAsmVersion>
+    <MicrosoftNETCoreILAsmVersion>3.0.0-preview-27318-01</MicrosoftNETCoreILAsmVersion>
     <MicrosoftNETTestSdkVersion>15.8.0</MicrosoftNETTestSdkVersion>
     <MicrosoftVisualFSharpTypeProvidersRedistVersion>1.0.0</MicrosoftVisualFSharpTypeProvidersRedistVersion>
     <MicrosoftWin32RegistryVersion>4.3.0</MicrosoftWin32RegistryVersion>