TDD & DDD from the Ground Up • Christopher Simon • GOTO 2025

This presentation was recorded at GOTO Copenhagen 2025. #GOTOcon #GOTOcph
https://gotocph.com

Christopher Simon - Live Coding Technology Coach @ChrisSimonAu 

RESOURCES
https://bsky.app/profile/chrissimon.au
https://hachyderm.io/@ChrisSimonAu
https://twitter.com/ChrisSimonAu
https://github.com/chrissimon-au
https://www.linkedin.com/in/chrissimon-au
https://chrissimon.au

Links
https://github.com/chrissimon-au/tdd-ddd-demo-java
https://contextive.tech

ABSTRACT
Are you interested in using Domain-Driven Design (DDD) to create maintainable and scalable software, but not sure how to get started?
Or perhaps you've heard that DDD is only suitable for complex domains - and when starting out, you're not sure if your project will need it?

Join me for a live coding demonstration that will show you how to apply Test-Driven Development (TDD) from the very beginning of a project so you can bring DDD in when you need it.

We'll start with the simplest possible implementation - a basic CRUD system to help a university handle student enrolments. We'll gradually add more complex requirements, such as the need to ensure courses don't become over-enrolled - which will prompt us to do some code-smell refactoring, strangely enough arriving at things that start to look like the DDD tactical patterns of repositories, aggregates and domain services.

In implementing these requirements, inspiration will strike! What if the model were changed - what if we allowed all enrolments and then allocated resources to the most popular courses as required so we never have to prevent a student from enrolling?
We'll now see how the TDD tests and the neatly refactored domain models make it much easier to embark on this dramatic change - in other words, how much more maintainable our DDD codebase has become.

The code in this demo is available in either C# or Java - the audience will vote on the day which language is used! [...]

TIMECODES
00:00 Intro
03:35 Demo
40:05 Event Storming
42:16 Demo
45:55 Outro

Download slides and read the full abstract here:
https://gotocph.com/2025/sessions/3624

RECOMMENDED BOOKS
Kent Beck • Test Driven Development • https://amzn.to/4qqyXxr
Saleem Siddiqui • Learning Test-Driven Development • https://amzn.to/35OMb3n
Eric Evans • Domain-Driven Design • https://amzn.to/3tnGhwm
Vaughn Vernon • Implementing Domain-Driven Design • https://amzn.to/3o0KZjl
Vaughn Vernon • Domain-Driven Design Distilled • https://amzn.to/3IEufpT

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