If display is not set, do not attempt to run application

Tests/Wrapping/qtwrappingmain.cxx

@@ -1,13 +1,29 @@
 #include <qapplication.h>
 #include "qtwrapping.h"
 
+#ifndef _WIN32
+# include <stdlib.h>
+# include <stdio.h>
+#endif
+
 int main(int argc, char *argv[])
 {
-
+#ifndef _WIN32
+  const char* display = getenv("DISPLAY");
+  if ( display && strlen(display)>0 )
+    {
+#endif
     QApplication app(argc,argv);
 
     qtwrapping qtw;
     app.setMainWidget(&qtw);
+#ifndef _WIN32
+    }
+  else
+    {
+    printf("Environment variable DISPLAY is not set. I will pretend like the test passed, but you should really set it.\n");
+    }
+#endif
 
   return 0;
 }