Analyse details of TYPO3 extensions
TYPO3 extension can be downloaded from the TYPO3 Extension repository ("TER") by using the Extension Manager in the backend.
These extension are installed in the directory typo3conf/ext/
System extensions are extensions that are shipped with the Core package and can be found in typo3/sysext/ (parts of our solution will be a system extension)
Optional: Learn how to use PHPUnit in TYPO3 by downloading the TYPO3 extension "phpunit".
Unit tests of the TYPO3 Core are in tests/, tests of extensions are in the same directory of each extension.
I would be nice, if our new solutions have unit tests by default.