From 9b828b16c4d9b08dbacebd201be31cbec4e0403a Mon Sep 17 00:00:00 2001
From: Matthew Bratschun <25390936+mbrat2005@users.noreply.github.com>
Date: Mon, 6 Jan 2025 07:52:12 -0700
Subject: [PATCH] fix issue comparing empty lb backend pool list to NIC backend
 pool list (#131)

---
 .../AzureBasicLoadBalancerUpgrade.psd1                 |  4 ++--
 .../modules/ValidateScenario/ValidateScenario.psm1     | 10 +++++++++-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/AzureBasicLoadBalancerUpgrade/module/AzureBasicLoadBalancerUpgrade/AzureBasicLoadBalancerUpgrade.psd1 b/AzureBasicLoadBalancerUpgrade/module/AzureBasicLoadBalancerUpgrade/AzureBasicLoadBalancerUpgrade.psd1
index 06535a12..fb795824 100644
--- a/AzureBasicLoadBalancerUpgrade/module/AzureBasicLoadBalancerUpgrade/AzureBasicLoadBalancerUpgrade.psd1
+++ b/AzureBasicLoadBalancerUpgrade/module/AzureBasicLoadBalancerUpgrade/AzureBasicLoadBalancerUpgrade.psd1
@@ -12,7 +12,7 @@
     RootModule = 'AzureBasicLoadBalancerUpgrade'
 
     # Version number of this module.
-    ModuleVersion = '2.4.14'
+    ModuleVersion = '2.4.15'
 
     # Supported PSEditions
     # CompatiblePSEditions = @()
@@ -107,7 +107,7 @@
             # IconUri = ''
 
             # ReleaseNotes of this module
-            ReleaseNotes = 'Added support to retain AutomaticOSUpgrade setting when App Health extension is used instead of health probe.'
+            ReleaseNotes = 'Fix bug when comparing backend pool membership on empty LBs.'
 
             # Prerelease string of this module
             # Prerelease = 'beta'
diff --git a/AzureBasicLoadBalancerUpgrade/module/AzureBasicLoadBalancerUpgrade/modules/ValidateScenario/ValidateScenario.psm1 b/AzureBasicLoadBalancerUpgrade/module/AzureBasicLoadBalancerUpgrade/modules/ValidateScenario/ValidateScenario.psm1
index 5950dc85..8afbab9b 100644
--- a/AzureBasicLoadBalancerUpgrade/module/AzureBasicLoadBalancerUpgrade/modules/ValidateScenario/ValidateScenario.psm1
+++ b/AzureBasicLoadBalancerUpgrade/module/AzureBasicLoadBalancerUpgrade/modules/ValidateScenario/ValidateScenario.psm1
@@ -407,8 +407,16 @@ Function Test-SupportedMigrationScenario {
         ## compare nic backend pool memberships to basicLBBackendIds
         try {
             $nicBackendPoolMembershipsIds = @()
+
             $nicBackendPoolMembershipsIds += $basicLBVMNics.IpConfigurations.loadBalancerBackendAddressPools.id | Sort-Object | Get-Unique
-            $differentMembership = Compare-Object $nicBackendPoolMembershipsIds $basicLBBackendIds
+
+            If ([string]::IsNullOrEmpty($basicLBBackendIds)) {
+                # handle LBs with no backend pools
+                log -Message "[Test-SupportedMigrationScenario] No Basic Load Balancer backend pool IDs provided, so all NIC backend pool IDs must be on another LB (if any)." -Severity Debug
+            }
+            Else {
+                $differentMembership = Compare-Object -ReferenceObject $nicBackendPoolMembershipsIds -DifferenceObject $basicLBBackendIds
+            }
         }
         catch {
             $message = "[Test-SupportedMigrationScenario] Error comparing NIC backend pool memberships ($($nicBackendPoolMembershipsIds -join ',')) to basicLBBackendIds ($($basicLBBackendIds -join ',')). Error: $($_.Exception.Message)"