Important: #80606 - Testing Framework Removal / Use composer package instead

See Issue #80606

Description

The TYPO3 core base testing classes were moved to a separate composer package and removed from the TYPO3 core. If you want to continue using the testing framework classes please use composer and require the package typo3/testing-framework.

To make sure you don't run into path issues, you can set the following environment variable: TYPO3_PATH_ROOT = The path to your TYPO3 root directory

Find the new package on github

And on packagist