Unskip build task integration tests

eng/build-utils.ps1

@@ -269,3 +269,21 @@ function Unsubst-TempDir() {
     $env:TMP=$originalTemp
   }
 }
+
+function EnablePreviewSdks() {
+  $vsInfo = LocateVisualStudio
+  if ($vsInfo -eq $null) {
+    # Preview SDKs are allowed when no Visual Studio instance is installed
+    Write-Host "No Visual Studio installation found; skipping enabling preview SDKs"
+    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"
+  Write-Host "Enabling preview SDKs by writing to $sdkFile"
+  'UsePreviews=True' | Set-Content $sdkFile
+}

eng/build.ps1

@@ -541,22 +541,6 @@ function TestUsingRunTests() {
   }
 }
 
-function EnablePreviewSdks() {
-  $vsInfo = LocateVisualStudio
-  if ($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
-}
-
 # Deploy our core VSIX libraries to Visual Studio via the Roslyn VSIX tool.  This is an alternative to
 # deploying at build time.
 function Deploy-VsixViaTool() {

eng/enable-preview-sdks.ps1

@@ -0,0 +1,6 @@
+Set-StrictMode -version 2.0
+$ErrorActionPreference="Stop"
+
+. (Join-Path $PSScriptRoot "build-utils.ps1")
+
+EnablePreviewSdks

src/Compilers/Core/MSBuildTaskTests/TestUtilities/IntegrationTestBase.cs

@@ -123,7 +123,7 @@ protected static ProcessResult RunCommandLineCompiler(
     /// <param name="overrideToolExe">
     /// Setting ToolExe to "csc.exe" should use the built-in compiler regardless of apphost being used or not.
     /// </param>
-    [Theory(Skip = "https://github.com/dotnet/roslyn/issues/80991"), CombinatorialData]
+    [Theory, CombinatorialData]
     [WorkItem("https://devdiv.visualstudio.com/DevDiv/_workitems/edit/2615118")]
     public void SdkBuild_Csc(bool useSharedCompilation, bool overrideToolExe, bool useAppHost)
     {
@@ -195,7 +195,7 @@ class Program { static void Main() { System.Console.WriteLine("Hello from file")
     /// <param name="overrideToolExe">
     /// Setting ToolExe to "vbc.exe" should use the built-in compiler regardless of apphost being used or not.
     /// </param>
-    [Theory(Skip = "https://github.com/dotnet/roslyn/issues/80991"), CombinatorialData]
+    [Theory, CombinatorialData]
     [WorkItem("https://devdiv.visualstudio.com/DevDiv/_workitems/edit/2615118")]
     public void SdkBuild_Vbc(bool useSharedCompilation, bool overrideToolExe, bool useAppHost)
     {

src/Tools/Source/RunTests/HelixTestRunner.cs

@@ -215,6 +215,13 @@ static void AppendHelixWorkItemProject(
                 Path.Combine(workItemPayloadDir, rspFileName),
                 GetRspFileContent(assemblyRelativeFilePaths, helixWorkItem.TestMethodNames, platform));
 
+            Directory.CreateSymbolicLink(
+                path: Path.Combine(workItemPayloadDir, "eng"),
+                pathToTarget: Path.Combine(artifactsDir, "..", "eng"));
+            File.CreateSymbolicLink(
+                path: Path.Combine(workItemPayloadDir, "global.json"),
+                pathToTarget: Path.Combine(artifactsDir, "..", "global.json"));
+
             var (commandFileName, commandContent) = GetHelixCommandContent(assemblyRelativeFilePaths, rspFileName, testOS);
             File.WriteAllText(Path.Combine(workItemPayloadDir, commandFileName), commandContent);
 
@@ -283,6 +290,8 @@ static void AppendHelixWorkItemProject(
 
             command.AppendLine(isUnix ? "env | sort" : "set");
 
+            command.AppendLine("powershell -ExecutionPolicy ByPass -NoProfile -File ./eng/enable-preview-sdks.ps1");
+
             // Rehydrate assemblies that we need to run as part of this work item.
             foreach (var assemblyRelativeFilePath in assemblyRelativeFilePaths)
             {