Can't get view helper plugin tests to include the correct Rails core code

Hi,

I have a plugin that adds some view helpers to generate html. The
plugin is small and seems to work fine but I'd like to add some tests.
I've tried following some tutorials on the web for making plugin tests
and also looked in some of technoweenie's plugins to try and figure
this out but I keep getting errors. The problem seems to be trying to
include the correct code from the Rails core.

I've tried two version with two similar errors which are listed below.
Any ideas?

Thanks,
Peter