sync: improved unit tests

refs: #4264

Change-Id: I981f3d8f653e4750ee6f9d77f2c89188f11d8ebb
diff --git a/src/lsdb.hpp b/src/lsdb.hpp
index 042d727..4574242 100644
--- a/src/lsdb.hpp
+++ b/src/lsdb.hpp
@@ -51,8 +51,10 @@
   }
 
   bool
-  doesLsaExist(const ndn::Name& key, const std::string& lsType);
+  isLsaNew(const ndn::Name& routerName, const std::string& lsaType, const uint64_t& sequenceNumber);
 
+  bool
+  doesLsaExist(const ndn::Name& key, const std::string& lsType);
 
   /*! \brief Builds a name LSA for this router and then installs it
       into the LSDB.