Copy Site Collection from Live to Test in SharePoint 2013

I needed a customer site collection on my test environment. But we had different SharePoint versions (live PU and test SP1 of SPS2013). So we were not able to use PowerShell with Backup-SPSite and Restore-SPSite.

Solution was:

• Backup Content Database of Site Collection
• Copy Backup to test environment
• Restore backup on test SQL server in new database
• Set db owner to test farm administrator
• use PowerShell: Mount-SPContentDatabase "MyDatabaseName" -WebApplication http://sitename:port -AssignNewDatabaseId
• Open central administration, check if content database is assigned to web application
• add a correct site collection administrator 

Thanks to our SharePoint technical support team @S-PI!