On office 365 we created one site collection name "https://abc.sharepoint.com/teams/testsite" where we have all our development, now we want to move our content from testsite to abc.sharepoint.
Please let me know if there are any ways to do his.
have you tried saving your source site collection as Template ?
Try saving it as Site-Template by adding the site in your network locations as described in This Link. Let me know if it was useful to you.
Edit for Publishing Issue :
Try enabling the "SaveSiteAsTemplateEnabled" to True from SPD.
This entry shows for the SharePoint on-prem, but I think it might work in SP-online as well.