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In a startup, you need to engineer to minimize the latency of validating features. Sometimes tests help with that (like when you're dealing with a complicated algorithm), sometimes they don't. I wrote a poker engine recently and I had many tests for the engine itself, a few tests for the tricky parts of the UI, and no tests at all for the system as a whole.

The challenge is that when you get into scaling, you need to begin engineering for throughput, which requires a completely different engineering style focused on higher throughput and reduced variance. This style is well supported by "test absolutely everything" TDD.

Oh, and then when you want to do a tangential experiment, you want to go back to latency-oriented engineering, but without destabilizing existing code.

In short, I'd say yes, it's plausible that overuse of TDD could be hampering a startups agility.

1 comments

So when you say "minimize the latency of validating features" do you mean that you want to reduce the time between building something and getting feedback from your users? Can you elaborate on this point? What is latency-oriented engineering?

I think you have it right. Latency-oriented engineering is a style of development that minimizes the time through the entire loop from idea to learning to feedback from real users to learning based on that feedback to the next idea. What you do to achieve this is very different when you have a bare idea and no customers or when you have a million daily users. The goals is the same--minimize the loop.

Hi Kent,

I wanted to reply to your comment...

How do I apply the theory of latency-oriented engineering to the following real world problem? I have an idea for a book that might be called “Simple Code". It presents a decision-language to help software engineers make good design decisions. My idea is in the very beginning stages (4 days in) so it is vague; but it would incorporate XP theories and practices, especially TDD. The set of rules in the decision-language might be similar to rules in a game. I’m not sure if this “idea” of mine is a book at all. It might be a web-based tool for searching "reliable" sources or it might simply be a new language. The project is going to be my first attempt at merging my art with my software engineering skills. Whatever form it takes, it will be inspired by art, nature, and minimalism. If it's a book, it will be small enough to read in bed. How would I use latency-oriented engineering to minimize the loop from idea to learning to feedback from real users? How much of this project do I have to imagine/articulate/build in order to get feedback from real users? How do I get that feedback? Also, how do I justify the expense, i.e. the time needed to complete one loop, to my investors (my husband)?

Thanks.