There are a couple of similar questions but my issue seems different as I am basically copying a file that's currently working.
I joined a team where the last person left a cucumber/ruby framework with the following set up:
NameError: uninitialized constant PageTwo
Finally, I found it. It seems it was an issue with this particular project.
There was a file which was loading the CLASSES in real time, although they were hard coding part of the file name, hence that my new file was not found, ie,
they were loading *1.rb pages, whereas I made a copy and rename it to page2.rb...