I'd like to make a test copy of my live site on the same server. That is: to make a copy of my live site files to separate folder that points to the same MySQL server as live database but different database name.

livesitefiles->mysqldb1
testsitefiles->testmysqldb1

sitefiles and db's are the same at both locations.

Anything should I look out for? Can it happen that while I'm applying changes or adding content to test site the changes are applied to live sites database? I know I have to make updates in mainfile.php, but how about other changes, is there some cached files should I get rid off or anything else? Thanks for info.

As far as I can see you have two different XOOPS installations and there is no interaction between the two so nothing can go wrong. Most likely error is making changes in the wrong XOOPS install by accident.
The only reason I can think of for wanting to do it this way is so you have a test site to make changes on before you make the changes in the production website.
If you want a construction as the one you describe for backup purposes I would look into the use of cron-jobs and having an offline copy of the XOOPS files and database.

Kind regards Highlander

But I do not wan't to have two separate installations. Any time I do wan't to do any updates I wan't to copy my live site folder, point it to live sites backup database and make test changes. If there are no side effects I then I apply to main site. Questions was:

Is there a possibility while making changes to test site to make accidental changes in both databases?

Yes, I can make different user who has access only to this database, but can there be some references to old database? Can database write/access/supply data to old site folder?

I'm just brainstorming because I have never had a live and testlive server and databases on the same servers.

Thanks.