Advanced check validation: HTML content.

I would like to have validation check (just like the one in simple HTTPS checks) of “HTML should contain”.

I have highly dynamic website I would like to validate with transaction check. The problem is that I don’t have any stable css selectors to use for validation (every ID is randomly generated per deployment version). I can’t use simple HTTPS checks as there are cases where content load down the line might break the website and simple HTTPS check would respond to first 200 encountered.

The idea would be to: go to page > sleep > see if HTML looks as it should based on existence of strings, but that’s not an option — can only validate head/title/css selectors, etc..