What is the reason for conducting a PHP_VERSION test at the start of phpunit?

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The reason for conducting a PHPVERSION test at the start of phpunit is to ensure that the version of PHP being used is compatible with the version of PHPUnit being used. PHPUnit may have certain requirements for PHP versions or certain features that are dependent on specific PHP versions. By conducting the PHPVERSION test, PHPUnit can determine if it is safe to run the tests or if any updates or changes need to be made to the environment before proceeding.