[tests]: fix compile test issue

Add corresponding field in test_routesync.cpp

Signed-off-by: Yuqing Zhao <[email protected]>

Author: GaladrielZhao

tests/mock_tests/fpmsyncd/test_routesync.cpp

@@ -831,14 +831,16 @@ TEST_F(FpmSyncdResponseTest, TestRouteMsgWithNHG)
 
         vector<FieldValueTuple> fvs;
         EXPECT_TRUE(route_table.get(test_destipprefix, fvs));
-        EXPECT_EQ(fvs.size(), 3);
+        EXPECT_EQ(fvs.size(), 4);
         for (const auto& fv : fvs) {
             if (fvField(fv) == "nexthop") {
                 EXPECT_EQ(fvValue(fv), test_gateway);
             } else if (fvField(fv) == "ifname") {
                 EXPECT_EQ(fvValue(fv), "Ethernet1");
             } else if (fvField(fv) == "protocol") {
                 EXPECT_EQ(fvValue(fv), "static");
+            } else if (fvField(fv) == "nexthop_group") {
+                EXPECT_EQ(fvValue(fv), "na");
             }
         }
     }