Sync eng/common directory with azure-sdk-tools for PR 1559 (#2123)

* Handle empty files in Test-SampleMetadata

Relates to Azure/azure-sdk-for-java#20684

* Remove condition from verify-samples

* Use forward slash in path

* Fix directory typo

Co-authored-by: Heath Stewart <heaths@microsoft.com>

eng/common/pipelines/templates/steps/verify-samples.yml

@@ -5,15 +5,11 @@ parameters:
   - name: ScriptDirectory
     type: string
     default: eng/common/scripts
-  - name: Condition
-    type: boolean
-    default: succeeded()
 
 steps:
   - pwsh: |
       # If the last path segment is an absolute path it will be used entirely.
-      $root = [System.IO.Path]::Combine('$(Build.SourcesDireectory)', 'sdk', '${{ parameters.ServiceDirectory }}')
-      Get-ChildItem $root -Filter *.md -Recurse | ${{ parameters.ScriptDirectory }}\Test-SampleMetadata.ps1 -AllowParentProducts
+      $root = [System.IO.Path]::Combine('$(Build.SourcesDirectory)', 'sdk', '${{ parameters.ServiceDirectory }}')
+      Get-ChildItem $root -Filter *.md -Recurse | ${{ parameters.ScriptDirectory }}/Test-SampleMetadata.ps1 -AllowParentProducts
     displayName: Verify sample metadata
     workingDirectory: $(Build.SourcesDirectory)
-    condition: ${{ parameters.Condition }}

eng/common/scripts/Test-SampleMetadata.ps1

@@ -31,11 +31,13 @@ process {
         }
 
         [string[]] $content = $file | Get-Content
-        if (!$content[0].StartsWith('---')) {
+        if (!$content -or !$content[0].StartsWith('---')) {
             Write-Verbose "Skipping $($file.FullName): does not contain frontmatter"
             continue
         }
 
+        Write-Verbose "Checking $($file.FullName)"
+
         # Reset metadata and create mutable collections.
         $products = [System.Collections.Generic.List[string]]::new()