In order to run tests, the best way is to create a create a file .env at the root directory of this repository (next to the file package.json) and add environment variables like this:
WIFI_IFACE=<iface>
WIFI_SSID=<ssid>
WIFI_PASSWORD=<password> # put "" if you want an empty password.
See the module dotenv for the complete documentation of the file .env.
Then start a test with command node test/test-scan.js