[muxorch] Adding case for maintaining current state (sonic-net#2280)

* [muxorch] Adding case for maintaining current state

What I did:
Added a case where if current and previous Mux states are the same, post a log entry that acknowleges this change and returns without doing anything.

orchagent/muxorch.cpp

@@ -451,13 +451,19 @@ void MuxCable::setState(string new_state)
     new_state = muxStateValToString.at(ns);
 
     auto it = muxStateTransition.find(make_pair(state_, ns));
-
     if (it ==  muxStateTransition.end())
     {
         // Update HW Mux cable state anyways
         mux_cb_orch_->updateMuxState(mux_name_, new_state);
-        SWSS_LOG_ERROR("State transition from %s to %s is not-handled ",
-                        muxStateValToString.at(state_).c_str(), new_state.c_str());
+        if (strcmp(new_state.c_str(), muxStateValToString.at(state_).c_str()) == 0)
+        {
+            SWSS_LOG_NOTICE("[%s] Maintaining current MUX state", mux_name_.c_str());
+        }
+        else
+        {
+            SWSS_LOG_ERROR("State transition from %s to %s is not-handled ",
+                            muxStateValToString.at(state_).c_str(), new_state.c_str());
+        }
         return;
     }
 

tests/test_mux.py

@@ -95,7 +95,11 @@ class TestMuxTunnelBase():
     TC_TO_QUEUE_MAP = {str(i):str(i) for i in range(0, 8)}
     DSCP_TO_TC_MAP = {str(i):str(1) for i in range(0, 64)}
     TC_TO_PRIORITY_GROUP_MAP = {str(i):str(i) for i in range(0, 8)}
-
+
+    def check_syslog(self, dvs, marker, err_log, expected_cnt):
+        (exitcode, num) = dvs.runcmd(['sh', '-c', "awk \'/%s/,ENDFILE {print;}\' /var/log/syslog | grep \"%s\" | wc -l" % (marker, err_log)])
+        assert num.strip() >= str(expected_cnt)
+
     def create_vlan_interface(self, dvs):
         confdb = dvs.get_config_db()
 
@@ -309,6 +313,15 @@ def create_and_test_neighbor(self, confdb, appdb, asicdb, dvs, dvs_route):
         self.check_neigh_in_asic_db(asicdb, self.SERV2_IPV4)
         self.check_neigh_in_asic_db(asicdb, self.SERV2_IPV6)
 
+        marker = dvs.add_log_marker()
+
+        self.set_mux_state(appdb, "Ethernet0", "active")
+        self.set_mux_state(appdb, "Ethernet0", "active")
+        self.check_syslog(dvs, marker, "Maintaining current MUX state", 1)
+
+        self.set_mux_state(appdb, "Ethernet0", "init")
+        self.check_syslog(dvs, marker, "State transition from active to init is not-handled", 1)
+
     def create_and_test_fdb(self, appdb, asicdb, dvs, dvs_route):
 
         self.set_mux_state(appdb, "Ethernet0", "active")