tests/tiup-cluster: check result of pd scale-in

tests/tiup-cluster/script/scale_core.sh

@@ -58,10 +58,17 @@ function scale_core() {
     echo "start scale in pd"
     tiup-cluster $client --yes scale-in $name -N $ipprefix.103:2379
     wait_instance_num_reach $name $total_sub_one $native_ssh
+
+    # validate https://github.com/pingcap/tiup/issues/786
+    # ensure that this instance is removed from the startup scripts of other components that need to rely on PD
+    tiup-cluster $client exec $name -N $ipprefix.101 --command "grep -q $ipprefix.103:2379 /home/tidb/deploy/tidb-4000/scripts/run_tidb.sh && exit 1 || exit 0"
     echo "start scale out pd"
     topo=./topo/full_scale_in_pd.yaml
     sed "s/__IPPREFIX__/$ipprefix/g" $topo.tpl > $topo
     tiup-cluster $client --yes scale-out $name $topo
 
+    # after scalue-out, ensure this instance come back
+    tiup-cluster $client exec $name -N $ipprefix.101 --command "grep -q $ipprefix.103:2379 /home/tidb/deploy/tidb-4000/scripts/run_tidb.sh"
+
     tiup-cluster $client _test $name writable
 }