Lately I've been in the middle of development of an interesting project which soul and flash were mostly derived from Kickstarter and plenty of websites alike it. If somebody had said me back than, that one line of code in the configuration files of my project would make me as angry and tired as I was two weeks after writing that line, I'd laugh loudly. However, it was true - that line was goddamn hard for me to track down and mend.
I was rapidly developing my project, so I assumed it would be a good idea to add some registration-based and user-dependent functionality. Alright, I said. Time to include :confirmable module for Devise gem in my User model and get it working. SMTP-config setup, hiding credentials in Figaro files, a bit of view fixing and then first mail got it way to my testing email address. Everything was great, but... What did I see? Yes, user got his confirmation link, clicked on it and then he simply was not confirmed. WHAT? After lurking out the Devise guts I patched it to develop forward(basically letting user to use site without confirmation required), but the problem was still here, crawling around to catch me first time I miss and implement datetime-related functionality.
Yaaas, I guess you get what comes next - HERE COME THE DRUMS, other words, additional features that need time and dates to be a part of them. Nothing, literally nothing what had to be working with dates, time and timezones functioned for real. You pass a date or time, even basic :created_at to the DB via ORM and when you get it back it returns just nil. Nothing you try mends the problem. Resetting the DB? Naaah. Debugging saving process? Nope. The funniest thing was in fact the detail that every freaking date inserted in the DB appeared in it, according to the PostgreAdmin and other database administration programs information, but each time I tried to get it Rails returned me the oddity of nil. As you may presume, it really grounded my gears as if I was watching Uve Boll films for an entire week.
After all the failed tries and experiments on my project I was tired, angry and full of hate. Nils were everywhere in my mind and for the last shot I googled just literally the case I came across. In the middle of the first search page I saw this stackoverflow link and, oh... Flying Spaghetti Monster, it worked. For some reason, when you pass to the config of timezone the timezone in the wrong format, the application doesn't indicates any error or exception. It doesn't even point you are a dummy, no. It just gets it's ORM time and date operations broken, because without proper timezone given it does not properly interpret the dates in the DB and ends up taking back nils instead of any date at all. This is an awfully bad and hardly trackable behaviour for the advanced data mapping system as Active Record.
Summarizing the stuff written above I can tell you that every, even the smallest change in your code shall be thought over and mentioned in your documentation and changelists. Remember, even the smallest bug can get to stumble your entire solution working process the time you least expect it.