Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires phpunit/phpunit ~4.0|~5.0, found phpunit/phpunit[4.0.0, ..., 4.8.36, 5.0.0, ..., 5.7.27] but these were not loaded, because they are affected by security advisories ("PKSA-z3gr-8qht-p93v", "PKSA-w57n-mhp6-c9sd"). Go to https://packagist.org/security-advisories/ to find advisory details. To ignore the advisories, add them to the audit "ignore" config. To turn the feature off entirely, you can set "block-insecure" to false in your "audit" config.