$ sudo apt-get update
$ sudo apt-get install openscad-testing-data 

openscad-testing-data is installed in your system.

Make ensure the openscad-testing-data package were installed using the commands given below,

$ sudo dpkg-query -l | grep openscad-testing-data *

You will get with openscad-testing-data package name, version, architecture and description in a table

openscad-testing-data package basic information: