The name test is reserved by the Internet Engineering Task Force (IETF) in RFC 2606 (June 1999) as a domain name that is not intended to be installed as a top-level domain (TLD) in the global Domain Name System (DNS) of the Internet for production use.
dotTest is a small script which allows you to configure local .test domains to point to different ports on your machine. For example, if you're developing some software which consists of a frontend service (running on port 8000) and a backend service (running on port 8080), it can be more clear to use http://frontend.test and http://backend.test instead of http://localhost:8000 and http://localhost:8080. This is what dotTest allows.
You can install it with
pip install dottest and see the code and read instructions on GitHub.
Right now it's only confirmed to work on MacOS High Sierra (it uses
ifconfig as configured by default on MacOS High Sierra). There's no reason why it won't work on other *nix systems which use these tools. If you need support for a different set of tools for your system, please submit a pull request.
It also does not work with Windows at all. If you can make it work for Windows please submit a pull request.