Carl Jung coined the term "synchronicity" to describe events that at first appear coincidental but which are potentially meaningfully connected.... a "meaningful coincidence". I've been thinking about this for some time now: that the advent of Rich Internet Applications (RIAs) could potentially be a tremendous boon for encouraging boring old server-side unit testing. Now, you might be thinking: "the two are completely unrelated". You can't get much more disparate. RIAs are sexy, they're hip, they're sleek and fun and whizbang. Unit testing, on the other hand, has got to be the least sexy coding you can do. It's the toothless, saggy-butt, scraggy-haired 4th cousin of cool technologies, at least to many people. Cranking out animated heatmap hoogies in flex is toot sweet. Writing "assertEquals(4,query.recordcount)" ain't.

Back when I started writing web apps in CF, debugging was pretty simple because you had easy access to the information you needed in order to debug. You load a page. If you have problems, you maybe throw in a cfdump/cfabort. Or you submit a form and want to see that the DB update query code looks OK, so you comment out the redirect in your index.cfm file, and then look at the debug output at the bottom of the page to check that your database updates are as expected. Snip snap done. But when you're building richer interfaces, this work is often either done asynchronously using javascript (ajax), in which case you can't rely on your old tricks; or, even more difficult, it's done in a movie client (flex/flash, silverlight) and you're even further removed from the information you need in order to do your debugging.

The further removed you are from development-time access to debug information, the more time you spend debugging development-time problems.

Let that sink in. There is no cfdump/cfabort simplicity when your front end is a flash movie making remote calls to your backend CFCs. With richer interfaces, the time you spend debugging your backend code increases considerably. Not so sexy anymore, is it? But here's the thing: What if, rather than try to debug your code at runtime in the interface, you instead remove the interface from the equation. You stay in CF for your debugging. You get your CFDumps back. In short, you get closer to your data again... you get closer to the information you need to do your debugging. You're no longer so far removed.

This is where our ugly cousin, unit testing, comes in for the win. By testing your backend CF code with more CF code, you stay on the server and you catch your problems earlier. You codify the expectations of the code. You think more about the edge cases. You root out bugs earlier in the process and thereby make writing your RIA joyful again. You can focus your front-end efforts on the pizazz because you're not worrying so much that your queries are working as expected -- you've already worked out the server-side kinks in your tests. The common arguments against unit testing -- that it takes too much time, that you write too much code, etc -- start to fall away as it becomes apparent that the time savings you accrue start to overtake the lost time spent trying to debug server-side code from an RIA.

This is what I've been thinking about: that RIAs make it harder to debug server-side code. Therefore, they encourage more unit testing of server-side code because the value proposition of unit testing is clearer when put in contrast to the drudgery of runtime debugging the backend of an RIA.

Which leads to my moment of synchronicity today. I had planned on writing this blog post on how RIA development damn near requires backend TDD. Then, I came to work this morning, and in my feedreader was this: Indy Nagpal gave a presentation on server-side TDD at a recent RIA conference. Not at CFUnited or CFObjective or the local CFUG. At an RIA conference. I thought that was pretty cool, and it suggests to me that other (way smarter) people are thinking the same thing: that if you're writing rich internet apps, then server-side unit testing is getting harder to ignore.

--marc