Outside-in TDD in theory and practice

Many of us have heard about outside-in TDD. But maybe not everyone had a chance to actually see it in action. How can I apply it successfully? Can I avoid pitfalls? What would be the benefits?

In this session I'll first start with a bit of a theory, what are the ideas behind the outside-in approach and how it differs from inside-out. I'll show the connections between this technique and other ideas like "walking skeleton", ports & adapters architecture or domain-driven design. But the main part will be dedicated to actual coding. First, I'll do a live coding implementing one or two features on an existing system. Then it will be your turn to either try to recreate my steps and see for yourselves, or to take on where I left and implement some other features. As it is often practised in TDD, I'd encourage you to work in pairs or even mobs. Please bring your notebooks with Gradle and Java 11 installed!

As a base, I will be using some existing Java project. The project will be small enough to be understood very fast, we will not be starting from scratch. It will also be using Spring Boot and I'll be showing how to actually avoid problems with such frameworks rather than integrate with them, but I'll be showing both. The theory is, of course, applicable to other languages and frameworks.

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Your facilitator Jacek Bilski is a senior consultant at INNOQ. He’s especially interested in good engineering, the place where delivering business value and striving for technical excellence are in a balance. He has almost 15 years of experience working in Java on mostly backend systems, but was also working on topics like frontend, automation or testing. Every now and then he publishes something on his own blog (https://www.bilski.tech/), INNOQ one or on Twitter (@jacek_bilski).

The workshop is hosted by it-economics, https://www.it-economics.de/