test : save_data error form added.

test/overall_test.py

@@ -79,6 +79,9 @@ False
 >>> result = g.save_image(file_adr="")
 >>> result["status"]
 False
+>>> result = g.save_data(file_adr="")
+>>> result["status"]
+False
 >>> socket.socket = guard
 >>> g.generate()
 >>> g.plot(color=2,bgcolor=2)