* It is not easy to tell what a part is by measuring device characteristics and behaviour because there are so many different types of device that are supplied in the same style of package. You can have a: Diode; Bipolar Transistor (BJT); MOSFET; Insulated Gate Bipolar Transistor (IGBT); Thyristor or Silicon Controlled Rectifier (SCR); Silicon Controlled Switch (SCS); Gate Turn Off Thyristor (GTO); Triac; Quadrac; and maybe even some special purpose resistors; manufactured in the same style of package. You would need quite a clever test setup to be able to test any device and be able to work out what type of device it was and also protect against the possibility of destroying it in the process. * The easiest way is to read the part number and manufacturer's logo on the package and then do some googling to identify the part. This not easy for small parts because the part number may be shortened or repleced by a code that is specific to the manufacturer of that part.