Hi, my name is Dragan and im in IT since 1997. working in many areas that needs to be done to have a complete website working.
My expert skills for your testing in the first row: Linux administrator (i prefer CentOS but all others dist is mostly the same) so complete LAMP-LEMP stack is included, Drupal and WP in the first place of cms...
Testing for: Load and Performance website and server or servers (scale and performance), security issue, long-term maintenance, bugs, updates, optimization, compatibility, SEO, etc.
If i missed something sry, its fast typing...
Please be free to contact me if You need any further question.
Sincerely
Dragan