How to debug Rails app?

I have spent last few days (in Poland May 1st and 3rd are holidays, so early May is always a long weekend here :)) ) reading Pragmatic series and trying to understand Ruby on Rails…

My first concerns are troubles (at least I’ve encountered some, maybe I don’t know something) with debugging and documentation.

Auto-generated docs for Rails are quite good, but navigation and finding right information makes trouble. They are divided into docs generated to each part of rails (like actionpack, activerecord, etc..) I’m new to rails and thus I’m not sure whether to check actionpack or activesupport or other part of rails docs. But dealing with it was quite easy. And Google desktop was not needed ;-)) swish (http://swish-e.org/) is quite enough for me.

After having indexed all docs ;)) with Agile Web Development with Rails and Programming Ruby opened I’ve started to learn more. But then I needed sometimes to debug my application. Yeah, I’ve learned to use breakpoints, but breakpoints, however very handy have lack of one feature. Coming from compiled languages world I’m used to step and next commands in gdb. I don’t know way to use breakpoints, examine application state and step through application. Of course it is possible to put breakpoints in almost every interesting place, but this is both error prone and not effective.

I tried to be smart :))) and run require 'debug' directive in irb shell after connecting to application with breakpoint… Guess what? :))) whole thing (rails) hung… Bad luck… I’m pretty sure, there must be some way to do such thing!