Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires hiqdev/php-data-mapper dev-master -> satisfiable by hiqdev/php-data-mapper[dev-master]. - Root composer.json requires phpunit/phpunit ^12.0 -> satisfiable by phpunit/phpunit[12.0.0, ..., 12.4.x-dev (alias of dev-main)]. - phpunit/php-code-coverage[12.0.0, ..., 12.3.4] require nikic/php-parser ^5.4.0 -> satisfiable by nikic/php-parser[v5.4.0, ..., 5.x-dev (alias of dev-master)]. - phpunit/php-code-coverage dev-main requires nikic/php-parser ^5.6.1 -> satisfiable by nikic/php-parser[v5.6.1, 5.x-dev (alias of dev-master)]. - phpunit/phpunit[12.0.0, ..., 12.0.1] require phpunit/php-code-coverage ^12.0.0 -> satisfiable by phpunit/php-code-coverage[12.0.0, ..., 12.3.x-dev (alias of dev-main)]. - phpunit/phpunit[12.0.8, ..., 12.0.10] require phpunit/php-code-coverage ^12.1.0 -> satisfiable by phpunit/php-code-coverage[12.1.0, ..., 12.3.x-dev (alias of dev-main)]. - phpunit/phpunit[12.0.2, ..., 12.0.3] require phpunit/php-code-coverage ^12.0.2 -> satisfiable by phpunit/php-code-coverage[12.0.2, ..., 12.3.x-dev (alias of dev-main)]. - phpunit/phpunit[12.0.4, ..., 12.0.5] require phpunit/php-code-coverage ^12.0.3 -> satisfiable by phpunit/php-code-coverage[12.0.3, ..., 12.3.x-dev (alias of dev-main)]. - phpunit/phpunit[12.0.6, ..., 12.0.7] require phpunit/php-code-coverage ^12.0.4 -> satisfiable by phpunit/php-code-coverage[12.0.4, ..., 12.3.x-dev (alias of dev-main)]. - phpunit/phpunit[12.1.0, ..., 12.1.4] require phpunit/php-code-coverage ^12.1.2 -> satisfiable by phpunit/php-code-coverage[12.1.2, ..., 12.3.x-dev (alias of dev-main)]. - phpunit/phpunit[12.1.5, ..., 12.1.6] require phpunit/php-code-coverage ^12.2.1 -> satisfiable by phpunit/php-code-coverage[12.2.1, ..., 12.3.x-dev (alias of dev-main)]. - phpunit/phpunit[12.2.0, ..., 12.2.2] require phpunit/php-code-coverage ^12.3.0 -> satisfiable by phpunit/php-code-coverage[12.3.0, ..., 12.3.x-dev (alias of dev-main)]. - phpunit/phpunit[12.2.3, ..., 12.2.7] require phpunit/php-code-coverage ^12.3.1 -> satisfiable by phpunit/php-code-coverage[12.3.1, ..., 12.3.x-dev (alias of dev-main)]. - phpunit/phpunit[12.2.8, ..., 12.3.6] require phpunit/php-code-coverage ^12.3.2 -> satisfiable by phpunit/php-code-coverage[12.3.2, ..., 12.3.x-dev (alias of dev-main)]. - phpunit/phpunit 12.3.7 requires phpunit/php-code-coverage ^12.3.3 -> satisfiable by phpunit/php-code-coverage[12.3.3, ..., 12.3.x-dev (alias of dev-main)]. - phpunit/phpunit 12.3.8 requires phpunit/php-code-coverage ^12.3.6 -> satisfiable by phpunit/php-code-coverage[12.3.6, 12.3.7, 12.3.x-dev (alias of dev-main)]. - phpunit/phpunit dev-main requires phpunit/php-code-coverage ^12.3.7 -> satisfiable by phpunit/php-code-coverage[12.3.7, 12.3.x-dev (alias of dev-main)]. - Conclusion: don't install nikic/php-parser dev-master (conflict analysis result) - nikic/php-parser 5.x-dev is an alias of nikic/php-parser dev-master and thus requires it to be installed too. - phpunit/php-code-coverage 12.3.x-dev is an alias of phpunit/php-code-coverage dev-main and thus requires it to be installed too. - phpunit/phpunit 12.4.x-dev is an alias of phpunit/phpunit dev-main and thus requires it to be installed too.