Class with unit tests

I worked thru the changes in the email:
cleaning up the names
removing the duplicate unittests.
this method feels unecessary its just duplicating inbuild python. If its clear you've got a list, then people can write this bit themselves. Or if you use it in other places in the code, just write out len(col_name_list) there. That increases readability as it lets people scan through and they don't have to go and switch to another piece of code to see what's happening.