Watcher is simple tools to run your arbitrary command on file changes.
$ watcher <command> <file> (<file>)...
$ composer global require amad/watcher
$ watcher phpunit ./
$ watcher 'clear && phpunit -c phpunit.xml' src/ tests/
$ watcher 'docker run unitests' src/ tests/
$ watcher 'docker exec project-container behat' src/ tests/features/