Add verification for alternatives migration to extended upgrades test

Author: PeaceRebel

tests/kola/upgrade/extended/test.sh

@@ -244,6 +244,19 @@ selinux-sanity-check() {
 
 ok "Reached version: $version"
 
+verify-alternatives-migration() {
+    # Verify iptables migration
+    if [[ $(alternatives --admindir /etc/alternatives-admindir --display iptables | grep -c -E 'link currently points to /usr/(bin|sbin)/iptables-nft') != "1" ]]; then
+        fatal "Error: migration did not set iptables to nft backend"
+    fi
+    if [[ $(iptables --version | grep -c "nf_tables") != "1" ]]; then
+        fatal "Error: iptables not reset to nftables backend"
+    fi
+
+    ok "alternatives migration verification passed."
+
+}
+
 # Are we all the way at the desired target version?
 # If so then we can exit with success!
 if vereq $version $target_version; then
@@ -256,6 +269,8 @@ if vereq $version $target_version; then
     fi
     # One last check!
     selinux-sanity-check
+    #One more last check
+    verify-alternatives-migration
     exit 0
 fi