tests: extend refresh hold spread test checks

Signed-off-by: Miguel Pires <miguel.pires@canonical.com>

tests/main/snap-refresh-hold/task.yaml

@@ -2,6 +2,8 @@ summary: Check snap refresh hold and unhold
 
 prepare: |
   snap install test-snapd-tools
+  snap set system experimental.parallel-instances=true
+  snap install test-snapd-tools_instance
   snap install --devmode jq
 
 restore: |
@@ -12,6 +14,7 @@ restore: |
 execute: |
   reset() {
     snap refresh --channel=latest/stable test-snapd-tools
+    snap refresh --channel=latest/stable test-snapd-tools_instance
     snap refresh --unhold test-snapd-tools
     snap refresh --unhold
   }
@@ -35,10 +38,11 @@ execute: |
 
   systemctl stop snapd.{service,socket}
   "$TESTSTOOLS"/snapd-state change-snap-channel test-snapd-tools edge
+  "$TESTSTOOLS"/snapd-state change-snap-channel test-snapd-tools_instance edge
   "$TESTSTOOLS"/snapd-state force-autorefresh
   systemctl start snapd.{socket,service}
 
-  if retry -n 5 --quiet sh -c 'snap changes | tail -2 | grep "Done.*Auto-refresh"'; then
+  if retry -n 5 --quiet sh -c 'snap changes | tail -2 | grep "Done.*Auto-refresh snap "test-snapd-tools_instance""'; then
     echo "expected 'snap refresh --hold' to prevent auto-refresh"
     exit 1
   fi
@@ -57,7 +61,8 @@ execute: |
   echo "Held snaps don't refresh in general refreshes"
   reset
   snap refresh --hold=forever test-snapd-tools
-  snap refresh 2>&1 | MATCH "All snaps up to date."
+  snap switch --edge test-snapd-tools_instance
+  snap refresh 2>&1 | MATCH "test-snapd-tools_instance .* refreshed"
 
   echo "Held snaps are refreshed in specific refreshes"
   reset