I often do an exercise in the Rapid Software Testing class in which I ask people to catalog things that, for them, make testing harder or slower. Their lists fit a pattern I hear over and over from testers (you can see an example of the pattern in this recent question on Stack Exchange). Typical points include: I’m a tester working alone with several programmers (or one of a handful … Read more
In this series of blog posts, I’ve been talking about project estimation. But I’m a tester, and if you’re reading this blog, presumably you’re a tester too, or at least you’re interested in testing. So, all this has might have been interesting for project estimation in general, but what are the implications for test project estimation? Let’s start with the tester’s approach: question the question. Is there ever such a … Read more
Last time out, we determined that mucking with the estimate to account for variance and surprises in projects is in several ways wanting. This time, we’ll make some choices about the tasks and the projects, and see where those choices might take us. Leave Problem Tasks Incomplete; Accept Missing Features There are a couple of variations on this strategy. The first is to Blow The Whistle At 100. That is, … Read more
In the last post, I talked about the asymmetry of unexpected events and the attendant problems with estimation. Today we’re going to look at some possible workarounds for the problems. Testers often start by questioning the validity of models, so let’s start there. The linear model that I’ve proposed doesn’t match reality in several ways, and so far I haven’t been very explicit about them. Here are just a few … Read more
There has been a flurry of discussion about estimation on the net in the last few months. All this reminded me to post the results of some number-crunching experiments that I started to do back in November 2009, based on a thought experiment by James Bach. That work coincided with the writing of Swan Song, a Better Software column in which I discussed The Black Swan, by Nassim Nicholas Taleb. … Read more
The Agile community (to the degree that such a thing exists at all; it’s a little like talking about “the software industry”) appears to me to be really confused about what “done” means. Whatever “done” means, it’s subject to the Relative Rule. I coined the Relative Rule, inspired by Jerry Weinberg‘s definition of quality (“quality is value to some person(s)”). The Relative Rule goes like this: For any abstract X, … Read more
In our Rapid Testing class, James Bach and I like to talk about an underappreciated tester resource: disposable time. Disposable time is the time that you can afford to waste without getting into trouble. Now, we want to be careful about what we mean by “waste”, here. It’s not that you want to waste the time. You probably want to spend it wisely. It’s just that you won’t suffer harm … Read more
Over the last several months, B.J. Rollison has been delivering presentations and writing articles and blog posts in which he cites a paper Defect Detection Efficiency: Test Case Based vs. Exploratory Testing [DDE2007], by Juha Itkonen, Mika V. Mäntylä and Casper Lassenius (First International Symposium on Empirical Software Engineering and Measurement, pp. 61-70; the paper can be found here). I appreciate the authors’ intentions in examining the efficiency of exploratory … Read more
Yesterday I set up a thought experiment in which we divided our day of testing into three 90-minute sessions. I also made a simplifying assumption that bursts of testing activity representing some equivalent amount of test coverage (I called it a micro-session, or just a “test”) take two minutes. Investigating and reporting a bug that we find costs an additional eight minutes, so a test on its own would take … Read more
If you’re a tester, you’ve probably been asked, “Why is testing taking so long?” Maybe you’ve had a ready answer; maybe you haven’t. Here’s a model that might help you deal with the kind of manager who asks such questions. Let’s suppose that we divide our day of testing into three sessions, each session being, on average, 90 minutes of chartered, uninterrupted testing time. That’s four and a half hours … Read more