I came to Rails from PHP world, but I did not create any bigger project in PHP, so for me unit testing was new idea. Maybe not idea, but form with highly automated unit tests was quite new. So I had to start somewhere with tests and I can recommend for all beginners like me to start with manuals.rubyonrails.com/read/book/5. This reading is essential help with starting write own test.
The best thing I found to really get you into a test-first groove is “Test Driven Development”:http://www.amazon.com/exec/obidos/tg/detail/-/0321146530/104-1038581-4741539?v=glance by Kent Beck.
It’s the real deal when it comes to writing code test first, because it’s not something you do ? it’s a whole new frame of mind!
Good luck!
Damn, sorry about that link, though you were running Typo! Here it is again:
http://www.amazon.com/exec/obidos/tg/detail/-/0321146530/104-1038581-4741539?v=glance