Installer test: add static DNS configuration test

Driver installer supports restoring DNS configurations after driver
upgrade, so add a DNS checkpoint here.

Reference: The previous static IP configuration test was #3860
Signed-off-by: wji <wji@redhat.com>

qemu/tests/win_virtio_driver_update_by_installer.py

@@ -24,7 +24,10 @@ def run(test, params, env):
     5) Install driver from previous virtio-win.iso.
        Or virtio-win-guest-tool.
     6) Start virtio fs service on guest.
-    7) Upgrade driver via virtio-win-guest-tools.exe
+    7) Check for ip and dns loss before and after upgrade driver
+    7.1) Set ip and dns
+    7.2) Upgrade driver via virtio-win-guest-tools.exe
+    7.3) Check ip and dns loss
     8) Start virtio fs service on guest.
     9) Verify the qemu-ga version match expected version.
     10) Run driver signature check command in guest.
@@ -45,6 +48,15 @@ def change_virtio_media(cdrom_virtio):
         test.log.info("Changing virtio iso image to '%s'", virtio_iso)
         vm.change_media("drive_virtio", virtio_iso)
 
+    def check_dns_loss(session_serial):
+        static_dns_address = utils_net.get_windows_nic_attribute(
+                           session_serial, global_switch="nicconfig",
+                           key="MACAddress", value=f"{virtio_nic_mac}",
+                           target="DNSServerSearchOrder")
+        static_dns_address = static_dns_address.strip('{}').strip('"')
+        if static_dns_address != params["static_dns"]:
+            test.fail("Static dns is lost after upgrade driver, current dns is %s" % static_dns_address)
+
     devcon_path = params["devcon_path"]
     installer_pkg_check_cmd = params["installer_pkg_check_cmd"]
     run_install_cmd = params["run_install_cmd"]
@@ -96,6 +108,9 @@ def change_virtio_media(cdrom_virtio):
             static_ip_address = utils_net.get_guest_ip_addr(session_serial, virtio_nic_mac, os_type='windows')
             if static_ip_address != params["static_ip"]:
                 test.fail("Failed to setup static ip,current ip is %s" % static_ip_address)
+            setup_dns_cmd = params["setup_dns_cmd"] % ifname
+            session_serial.cmd_status(setup_dns_cmd)
+            check_dns_loss(session_serial)
         session_serial.close()
     else:
         for driver_name, device_name, device_hwid in zip(
@@ -128,6 +143,7 @@ def change_virtio_media(cdrom_virtio):
         static_ip_address = utils_net.get_guest_ip_addr(session_serial, virtio_nic_mac, os_type='windows')
         if static_ip_address != params["static_ip"]:
             test.fail("Static ip is lost after upgrade driver,current ip is %s" % static_ip_address)
+        check_dns_loss(session_serial)
         session_serial.close()
 
     # for some guests, need to reboot guest after drivers are updated