Start php-script in strace as if it where in the browser
Before start install php-cgi whith:
apt-get install php7.0-cgi
or
yum install php7-cgi
or something.
Start phptrace:
./phptrace -u http://www.test.com/var/www/test.php
Attention: script path in URL must point to the actual path to file ( /var/www/test.php or something )