Index: sources/canbus/caninterface.h
===================================================================
diff -u -r9a3ee027dbc33f39ee7df2a9dc5a7897c6b1854d -rf623529d6ec25b555f3ac2248d71fc2b5e7063d6
--- sources/canbus/caninterface.h	(.../caninterface.h)	(revision 9a3ee027dbc33f39ee7df2a9dc5a7897c6b1854d)
+++ sources/canbus/caninterface.h	(.../caninterface.h)	(revision f623529d6ec25b555f3ac2248d71fc2b5e7063d6)
@@ -23,6 +23,9 @@
 // Define
 #define _CanInterface CanInterface::I()
 
+// forward declarations
+class unittests;
+
 // namespace
 namespace Can {
 
@@ -37,18 +40,21 @@
 {
     Q_OBJECT
 
+    // friends
+    friend class ::unittests;
+
     // constants
-    const char *_canType        = "socketcan";
-    const char *_canInterface   = "can0";
-    const int   _canBitRate     = 250000;
+    const char    *_canType        = "socketcan";
+          QString  _canInterface   = "can0";
+    const int      _canBitRate     = 250000;
 
     // member variables
     QCanBusDevice *_canDevice = nullptr;
     qint64         _numberFramesWritten = 0;
     QString        _canStatus = "";
 
     // Singleton
-SINGLETON_DECL(CanInterface)
+    SINGLETON_DECL(CanInterface)
 public:
     bool init();
     void quit();