To build tSQLt on your local machine, clode the repository in a local folder:
git clone https://
Open that folder in Visual Studio Code, aka VSC (Open Source, download from https://code.visualstudio.com/download.)
You also need Docker Dektop (Free for non-commercial use, Download from https://www.docker.com/products/docker-desktop/.) This might work with other container platforms, too.
Once ready, type >Dev Containers: Open Folder in Container... into the top bar in VSC and hit Enter.
This starts up your development container, that includes all the software needed to build tSQLt.