Testing vs. Checking

Post-postscript: Think of this blog post with its feet up, enjoying a relaxing retirement after a strenuous career. Please read the new version first. In the years since the original post, I’ve further refined my take on the subject of testing and checking, mostly in collaboration with my colleague James Bach. Our current thinking on the topic appears on his blog, and I provide some followup here. We’ve also benefitted … Read more

The Tyranny of Always

I just spent $3,000 to get my nose fixed, and then I found out it was my tie that was crooked. —Steve Shrott There’s a piece of software development mythodology that suggests that it’s always more expensive to fix a problem late in the development process rather than early. Usually the ratios quoted are fantastic; a hundred to one, a thousand to one, ten thousand to one. Let’s put that … Read more

Test Estimation Is Really Negotiation

Some of this posting is based on a conversation from a little while back on If anyone has a problem with “test estimation”, here’s a thought experiment: Your manager (your client) wants to give you an assignment: to evaluate someone’s English skills, with the intention of qualifying him to work with your team. So how long would it take you to figure out whether a Spanish-speaking person spoke English … Read more

McLuhan on Blink Testing

At about the 10-minute mark in this video (from 1968) Marshall McLuhan refers to an expression that he claimed was then in use at IBM: “Information overload leads to pattern recognition.” This is central to the idea of what blink testing is all about. He also describes characteristics of the scientist’s mindset vs. the artist’s mindset, which reminded me of similar patterns that we might see in programmers and testers. … Read more