This script generates among other a custom packages.json enabling to deploy TYPO3 CMS packages by Composer. The file main file PackagesTYPO3CMSGenerator.php downloads the Git source, iterates over each tag and looks for the system extensions to resolve the correct dependencies. It will also generate some other files such as:

• packages-TYPO3Extensions-archive.json: contains all extensions including their respective versions which are older than the last quarter. The file is about 14 MB.
• packages-TYPO3Extensions-quarter.json: contains just the extension including their respective versions of the last quarter

Basically, packages.json "just" contains references to the other files identified by a sha1 hash and a name.

When launching the composer update or composer install command, Composer will download this packages.json file.

├── Build     -> Files for setting up this package and install dependencies.
├── Classes   -> PHP classes as its name indicates
├── Data      -> Temporary files
├── Web       -> Files visible by the outside world
├── build.xml -> Phing tasks

./bin/phpunit -c ./Build/UnitTests.xml [--colors]