test: fix and issue with the test-setup.ps1 script that was preventing it from being run from some version of powershell (#13834)

Co-authored-by: Ben Hillis <benhill@ntdev.microsoft.com>

tools/test/test-setup.ps1

@@ -71,23 +71,41 @@ if ($Package) {
     try {
         if ($AllowUnsigned)
         {
-            # unfortunately -AllowUnsigned isn't supported on vb so we need to manually import the certificate and trust it.
-            (Get-AuthenticodeSignature $Package).SignerCertificate | Export-Certificate -FilePath private-wsl.cert | Out-Null
-            try
-            {
-                Import-Certificate -FilePath .\private-wsl.cert -CertStoreLocation Cert:\LocalMachine\Root | Out-Null
+            # Try to add with -AllowUnsigned first (supported in newer PowerShell)
+            try {
+                Add-AppxPackage $Package -AllowUnsigned -ErrorAction Stop
             }
-            finally
-            {
-                Remove-Item -Path .\private-wsl.cert
+            catch {
+                # Fallback: manually import the certificate and trust it
+                Write-Host "Attempting to import package certificate..."
+                $signature = Get-AuthenticodeSignature -LiteralPath $Package
+                if (-not $signature.SignerCertificate) {
+                    Write-Error "Package is not signed or has no certificate. Cannot import certificate."
+                    exit 1
+                }
+
+                $cert = $signature.SignerCertificate
+                $certPath = Join-Path $env:TEMP "wsl-package-cert.cer"
+                try {
+                    $cert | Export-Certificate -FilePath $certPath | Out-Null
+                    Import-Certificate -FilePath $certPath -CertStoreLocation Cert:\LocalMachine\Root | Out-Null
+                    Write-Host "Certificate imported successfully. Retrying package installation..."
+                }
+                finally {
+                    Remove-Item -Path $certPath -ErrorAction SilentlyContinue
+                }
+
+                # Retry installation after importing certificate
+                Add-AppxPackage $Package -ErrorAction Stop
             }
         }
-
-        Add-AppxPackage $Package
+        else {
+            Add-AppxPackage $Package -ErrorAction Stop
+        }
     }
     catch {
-        Write-Host $_
-        Get-AppPackageLog -All
+        Write-Host "Error installing package: $_"
+        Get-AppPackageLog | Select-Object -First 64 | Format-List
         exit 1
     }
 }