[Validate-TypeSpec.ps1] Add GitClean switch (#24933)

- Continuation of #24629

Author: ckairen

eng/pipelines/typespec-ci.yml

@@ -21,6 +21,6 @@ jobs:
     condition: succeededOrFailed()
 
   - pwsh: |
-      $(Build.SourcesDirectory)/eng/scripts/Validate-TypeSpec.ps1 $(Build.SourcesDirectory)
+      $(Build.SourcesDirectory)/eng/scripts/Validate-TypeSpec.ps1 $(Build.SourcesDirectory) -GitClean
     displayName: Validate All Specs
     condition: succeededOrFailed()

eng/pipelines/typespec-pr.yml

@@ -24,6 +24,7 @@ jobs:
       $(Build.SourcesDirectory)/eng/scripts/Validate-TypeSpec.ps1 `
         $(Build.SourcesDirectory) `
         "origin/${env:SYSTEM_PULLREQUEST_TARGETBRANCH}" `
-        "${env:SYSTEM_PULLREQUEST_SOURCECOMMITID}"
+        "${env:SYSTEM_PULLREQUEST_SOURCECOMMITID}" `
+        -GitClean
     displayName: Validate Impacted Specs
     condition: succeededOrFailed()

eng/scripts/Get-TypeSpec-Folders.ps1

@@ -13,6 +13,9 @@ $allChangedFiles = (Get-ChildItem -path ./specification tspconfig.yaml -Recurse)
 $allChangedFiles = $allChangedFiles -replace '\\', '/'
 
 if ([string]::IsNullOrEmpty($TargetBranch) -or [string]::IsNullOrEmpty($SourceBranch)) {
+  if ($TargetBranch -or $SourceBranch) {
+    throw "Please provide both target branch and source branch."
+  }
   $changedFiles = $allChangedFiles
 }
 else {

eng/scripts/Validate-TypeSpec.ps1

@@ -5,7 +5,9 @@ param (
   [Parameter(Position = 1, Mandatory = $false)]
   [string]$TargetBranch,
   [Parameter(Position = 2, Mandatory = $false)]
-  [string]$SourceBranch
+  [string]$SourceBranch,
+  [Parameter(Mandatory = $false)]
+  [switch]$GitClean
 )
 
 $exitCode = 0
@@ -25,8 +27,12 @@ if ($typespecFolders) {
     if ($LASTEXITCODE) {
       $exitCode = 1
     }
-    git restore .
-    git clean -df
+    if ($GitClean) {
+      Write-Host "git restore ."
+      git restore .
+      Write-Host "git clean -df"
+      git clean -df
+    }
   }
 }