This feature only does exact matching. It's not meant to be used for your use case. The intended use case is "reserving" usernames you want to keep for your own use, or which may be confusing to your visitors. For example, when you run a site with a support help desk (like ours) you do NOT want someone to subscribe as the name of the company, or as "helpdesk", "support", or something similar. The secondary use case is to forbid very offensive usernames, such as those pertaining to, uh, copulation with one's mother. I'll let your imagination fill in the gaps.
When you want to block patterns of usernames we have two existing features, WAF Deny List and Anti-spam Bad Words. Since these usernames are always followed by a dash or any other non-word character AND the word they use is definitely not something any regular visitors to your site would legitimately use you can and should use the Anti-spam Bad Words filtering feature. Adding Тест to the bad words would block the user creation forms with these usernames from being submitted.
IMPORTANT! This will not stop user creation through means that go outside of an interactive Joomla session, e.g. registering a user account with a social media login, or via an API. However, these are rather exotic use cases for the kind of problem you have and should not be an issue (which is to say, you'd have to explicitly configure something like that, in which case you'd know what's going on and how to deal with it).
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!
