Goto https://github.com/apache/airflow/ and fork the project.
Follow Codespaces Quickstart to start a new codespace.
Once the codespace starts your terminal should be already in
Breeze
environment and you should be able to edit and run the tests in VS Code interface.You can use Quick start quide for Visual Studio Code for details as Codespaces use Visual Studio Code as interface.
Follow the Quick start for typical development tasks.