tests: add RrsetFactory test

Change-Id: I7e1d19e5070c9ba5f25d2eea475897a99bac175a
diff --git a/src/daemon/rrset-factory.cpp b/src/daemon/rrset-factory.cpp
index 2830dac..9757abc 100644
--- a/src/daemon/rrset-factory.cpp
+++ b/src/daemon/rrset-factory.cpp
@@ -27,12 +27,12 @@
 
 NDNS_LOG_INIT("RrsetFactory")
 
-RrsetFactory::RrsetFactory(const std::string& dbFile,
+RrsetFactory::RrsetFactory(const boost::filesystem::path& dbFile,
                            const Name& zoneName,
                            KeyChain& keyChain,
                            const Name& inputDskCertName)
   : m_keyChain(keyChain)
-  , m_dbFile(dbFile)
+  , m_dbFile(dbFile.string())
   , m_zone(zoneName)
   , m_dskCertName(inputDskCertName)
   , m_checked(false)