Use Data to Split a God Class

Don’t Make Me Touch Ordering! The PM thought the feature was simple. And it should have been. Unfortunately, it requires making a tiny change to payment processing. And payment processing is part of the Order system…which is one monster class. More than half of our code depends on Order to do something. Each part of that code depends on the Order for a different set of responsibilities. Although there are patterns, the Order class’s sheer size and number of responsibilities […]

Isolating Dependencies with Ports and Adapters

My Service Interaction Tests are Slow and Fragile! Any legacy system needs to connect with other systems. However, coding and verifying changes in your legacy system requires the following things.  Simulate remote faults and verify your response. Verify that what you send to the remote system will cause it to do what you want it to do. Know when a release, rollback, or failover of the other system will change a behavior that you depend on. Change your released code’s […]

Creating and Shipping a Chimera

My product is written in the wrong language! Legacy systems tend to be old, and thus written in languages and frameworks that were available at the time they started. It’s no one’s fault, but the code is in the wrong language. This causes: Slow development. Difficult testing – my tech predates the TDD movement. Reinvention – libraries for new techniques are written in new languages. Difficult hiring – my tech predates most developers. More bugs – my tech needs more […]

From Hard to Easy: Changing Database Schema

I hate changing the database! Legacy databases present two challenges: Bad schema that is hard to change. Too much logic in the database. Both delay stories and generate bugs. Both waste your time and each will require thousands of person-hours to fix. We need to find a way to pay that cost incrementally; preferably divided among all the developers on the project. First let’s divide the problem in half by ignoring the logic for now. After all, lots of logic […]

Start Fixing a God Class

All I want to do is edit the freaking document! Unfortunately, so does everything. CDocument is central to what we do. Users think of documents, and so does the UI. Every piece of code reads the CDocument class…unless it modifies CDocument. And now I need to unit test my code. Also, I want to ship my team’s code independently of the other team. But every single feature touches CDocument. Many of them change CDocument – or one of the 6 […]

Make Tests Independent

I changed a piece of code and 75 tests broke… It was a simple feature. I just added a GDPR approval checkbox when creating a new account. And suddenly half our tests broke. Tests for reporting, tests for core features, all kinds of tests for all kinds of things. Because every one of them needed to create an account. So I added a default to the test mocks. I updated lots of expecteds. I added a startup step to some […]