RPM of PHPUnit version 5.7 are available in remi repository for Fedora ≥ 22 and for Enterprise Linux (CentOS, RHEL...).
This new major version requires PHP ≥ 5.6 (PHPUnit is available in remi, as PHP 5.4 and 5.5 have reached their EOL).
dnf --enablerepo=remi install phpunit
Installation, Enterprise Linux:
yum --enablerepo=remi,remi-php56 install phpunit
Notice: this tool is an essential component of PHP QA in Fedora. This version is also available in official repository of Fedora rawhide (so used by Koschei). I plan an update in Fedora 24 and 25 soon.