I took a look at the example you found. Please be aware that it is a CAN emulator, which also does SAE J1979 over CAN.
If you only need OBD2 for newer cars only using CANbus, you should be okay.
If you need OBD2 running on other protocols such as ISO9141, KWP2000, KWP fast init, PWM or VPW then you will need to keep on searching for something else.
I know there is a solution (a really cool one!) using old car parts here, but you have to choose a donor car that matches the protocol you are interested in:
Also, a RPi has been used as a CAN simulator as shown here:
I have not seen a simulator that does it all; I bet it exists as a commercial testing product...