Category: Software Engineering

On Test-Driven Development

I was having a conversation with someone the other day about unit testing. OK, actually I was interviewing someone for a Quality Engineering position on my team. We were talking about the difference between white-box tests that quality engineers write and tests that developers write.

I suggested that good white-box testers test the functionality and the failure cases (the intent of the function) and developers test the code that they’ve written (the function as coded). This then lead me to a new revelation around test-first development methodologies (or possibly reminded me of something I had forgotten).

I have been a proponent of writing tests first, since I first started doing Extreme Programming and read Kent Beck’s original book, Extreme Programming Explained: Embrace Change while working at Bootleg Networks (thanks Carmine for making me do that, by the way). Although admittedly, like many developers, I haven’t always been that rigorous at following that rule.

What I like about writing the tests before the function is that it clarifies my thinking about what the function should do, it alerts me to the corner cases, it gives me reasons to consider if the function is doing too much, and it gives me a way to instantly know if the function works once it is written. Writing the tests first also makes sure that the tests are written at all. Once the function is coded, it sometimes gets tempting to move on to the next bit of coding work with the intention of filling in the tests later.

What I hadn’t considered about writing the tests before the code is that it puts me into a quality mindset without having any bias to the code as I’d written it. I’m divorced from my own blind-spots around my coding. This actually leads me to writing better tests because I have no assumptions about how the code should work or fail. I’m testing the functionality, not the code.

Maybe I’d thought about this before, but I hadn’t really considered that benefit recently until that moment. Now, when I start to get lazy about writing my unit tests before my implementation, I’ll have a better reason to keep up my discipline.

A Couple New Pixel Bender Links

Frequent contributor to the Pixel Bender forums, Royi Avital, has released a new set of After Effects and Photoshop plug-ins written with Pixel Bender under the name Flixel Plugins. The first three are now available on aescripts.com

Flixel Plugins on aescripts.com

ApexVJ is a really beautiful Flash-based music visualizer that uses Pixel Bender

Simo Santavirta, the creator, wrote an article on his blog about it.

Moving on…

After many happy and productive years working on Pixel Bender and the Adobe Image Foundation, I’ve decided to take on some new challenges. I’m still at Adobe, but I’m now building a new team and launching a brand new product in the Photoshop family. I can’t say too much yet, but I will have news soon. I’ll still be posting about Pixel Bender stuff here (I’m still a very enthusiastic user!), but for the newest news, you should now also watch the official Pixel Bender blog.

A simple tip for prospective job seekers

If you are graduating with a degree in Computer Science and you are applying to companies in the software field; it is probably not a good idea to say something like “I’m looking for a job where I don’t have to sit in front of a computer all day” in your summary statement.

New Flash Experiment posted: Image Navigation via Overlay

screenshot I’ve been working on a lot of Pixel Bender experiments and wanted a nice UI to allow zooming in to examine the effected pixels. I decided to use the method of having an overlaid box on a scaled version of the image that corresponds to a zoomed separate display. I looked around and found some nice sample code on FLEX{er} written by Stelian Crisan. I mostly added nice UI to adjust the parameters in his code.

The experiment is posted on the labs area of my site.

Moving to scrum: changes

So we started this product cycle with two geographically-dispersed mixed-discipline scrum teams on two week sprints. Specifically, the geographical co-mingling was designed to break up some of the silos that had built up on the team due to the existing functional teams being in different cities. By the third sprint, we’ve now switched back to scrum teams that mimic the original functional and geographic splits and are now on four week cycles. This has made cross-team communication more difficult, but has made everyone a lot happier by keeping the scrum meetings more relevant to everyone on the team. I can definitely see why people like this more, it lets people focus on what they are doing, but I do think we are losing something by not spreading the knowledge of the different parts of the project around the team. Also, not having multiple functional areas represented in the scrum meetings means that some fresh perspectives are lost in any of the technical discussions that come up. Over the next few sprints we’ll try this out and see if this is working. I think this will probably be what we stick with, and we’ll need to address the cross-team communication issues separately.

Switching to four week sprints was mostly to reduce the amount of time spent in the scrum meetings themselves relative to the amount of working time. Between planning poker, retrospectives and sprint planning, a lot of time is lost to the process itself in a two week sprint. For a team used to working on 6 week sprints, fitting stories into 2 week chunks was also difficult. I like the idea of two week sprints, but in practice, it was difficult for a team that is new to scrum. We’ll maybe try 2 week sprints in a future product cycle.

We still haven’t switched to our planned internally created scrum tool which itself makes things difficult. Our backlog is an excel spreadsheet and our tracking is all on Wikis. Hopefully, we’ll be converted over to the tool by the next sprint, which should make life a bit easier on me and the scrum master.

Pixel Bender Synthesizer Experiment

The subject of using Pixel Bender for audio processing on the Flash platform comes up a lot. Audio processing is very processor-intensive and math-heavy, so it would seem natural to leverage Pixel Bender to improve performance of audio within a SWF. At some point, last year, I was talking to Justin Everett-Church about doing a demo for Flash Player 10.1 multi-touch features. A synth seemed like a good idea, and it would let me kill two birds with one stone. So I coded up a synth (with a lame Flex UI) and Justin took that and made it pretty and added multi-touch support. That 2nd part of the demo never worked out the way we meant it too (missed the MAX 2009 keynote by this much). After that, I planned on cleaning up the code and posting it, but I got busy shipping CS5 and well, 7 months later, I finally got around to posting it. Right now it is just the playable demo with the crummy Flex UI.

It is a total processor hog, on purpose. I basically wanted to use it to push the limit of what could be done in the player, so I kept adding more filters and processors to it until the audio started to break up on my Core Duo 2 Mac Book Pro and then stepped back just a little. It turns out that you can actually do a ton of audio processing interactively in the player leveraging Pixel Bender. This was also designed to run as an AIR app, which means that if you really want to play with it, close all your other tabs. Really.

UI for synth

Pixel Bender Synth Experiment
Continue reading “Pixel Bender Synthesizer Experiment”

Section 3.3.1 is not new behaviour from Apple

[disclaimer: I am an Adobe employee and an Adobe and Apple shareholder, my opinions are my own and not those of my employer.]

Like the rest of the software industry, I’ve been pondering what the effect section 3.3.1 of the iPhone 4.0 SDK will have. I had fully been planning to make an iPhone application at some point. I had planned to do the initial version with Flex to prototype, but then also spend time doing a Cocoa version to better learn that SDK for myself. This iPhone 4.0 SDK announcement honestly has me questioning if I do really want to develop for the iPhone. Not just because of a higher-minded sense of indignity at Apple’s lack of openness of their platform, but rather because of that combined with their somewhat arbitrary and opaque app store approval process. Could I spend months of my spare time learning ObjectiveC and working on an iPhone application only to have that time be a complete waste if the App store reviewers decide that they don’t want that app in the store?

Thinking about it this morning, I realized that not only was Apple’s move to lock in developers nothing new, but that I’d already written about it before (in fact, I’ve been blogging about it since almost the day I started doing professional development for the Macintosh): iPhone SDK: The carrot for Cocoa, the stick for Flash, The difference between being an Apple developer and a Microsoft developer, Developers Developers Developers Developers.

Gruber had the motivation right, I think, but I also think he got the ramifications wrong. Since Steve returned to Apple, they have been applying the screws tighter and tighter to their developers, trying to get them to lock in. It was somewhat indirect at first, but the long term implication was clear: “We’ll tell you how to develop for our platform, if you do as we say, then you’ll be fine. If you don’t do it the way we tell you, your life will be a never-ending stream of headaches.” The move to Intel (forcing all developers onto X-Code and a big rewrite of any PPC-assembly) was step one, the move to 64-bit (dropping support for Carbon after promising it) was step two. The iPhone 4.0 SDK is just the most obvious move in this process because it basically spells it out. You no longer have a choice: it is Apple’s way or the highway. The problem is the App store. On the Mac, I control my own distribution. On the iPhone platform, Apple does. That means that they no longer have to negotiate with their developers, they can now finally dictate to them.

As a developer, this makes the iPhone platform a lot less attractive because I also can’t be sure that they won’t change the terms again. Once I’m locked in, I’m locked in. Apple can do whatever they want and I’m forced to rewrite my apps or get forced out. As someone who writes software for a living, this scares the crap outta me.

Here are some other blog posts that I thought were good reading around this:
The iPad isn’t a computer, it’s a distribution channel (O’Reilly Radar)
Five rational arguments against Apple’s 3.3.1 policy (37 Signals blog)

Interesting UX presentation from Theresa Neil

RIA Screen Layouts

View more presentations from Theresa Neil.

The deck is a nice, loose, taxonomy of different design styles (some of the examples seem to have multiple styles to me), the examples are really good and actually pointed out some cool sites that I hadn’t heard about. Definitely worth a flip through if you have an interest in this stuff.

via Ahmed Rabieh

Moving to scrum: breakin’ the law

Well, part of the whole idea is that scrum isn’t a hard-and-fast set of rules right? I had some meetings at another office last week which necessitated moving out our first sprint review and retrospective a couple days. So if one of the guiding principals of scrum (and agile in general) is that the dates don’t change, everything else does, that got blown right out of the gate.

Some new stories came up as part of the sprint wrap-up which means that we’ll need to do a new planning poker session. Also, some other things came up which mean that there is a bit of housekeeping to do before we start the second sprint. We’re now in some uncharted zone between two sprints while the product manager and scrum master do some cleanup while the scrum teams do some off-book work for a couple days. Yeah, not ideal, but we’re trying to get it back on track. This sprint was going to be a throw-away anyway as it involved a lot of transition and getting used to the framework.

The retrospective brought up some really good issues and some innovative suggestions from the team on how to handle them. If the suggestions work out, I’ll post them here eventually.

There are still some folks unclear on what we expect to gain by transitioning to a new development process, but most of the team is embracing it as a good experiment and chance to try something new. For the most part, everyone seems to have an open mind and that definitely makes a huge difference as we all try to figure this out together. It hasn’t been the smoothest transition, but so far so good, I think. We’re definitely not as productive as we were before (so far). However, I think that the discipline provided by the product backlog means that we are actually getting the most important things done first. That makes a huge difference.