El Substack de Javier López Fernández

The intrinsic problems of software

During the last year I've seen a lot of people claiming against AI because it's not able to maintain the code, or the code is a mess or features have…

sep 28 • 

Javi lopez

4

1

The broken pipeline

People think that they need to avoid breaking the pipeline, it's not exactly like that. It's much better to be fast, fixing it.

sep 20 • 

Javi lopez

2

julio 2025

Don't test the structure

Tests are fitness functions that warn us about unintentional behaviors we have introduced when changing some parts of the code, breaking old behaviors.

jul 12 • 

Javi lopez

1

Mocking libraries are a powerful tool

Mocking tools make it really easy to create stubs, spies, mocks. When you start learning how to test you love them, then after a while you hate them and…

jul 6 • 

Javi lopez

3

junio 2025

Mistakes

Mistakes in software are opportunities to learn, but it's incredibly stupid to commit a mistake twice.

jun 28 • 

Javi lopez

mayo 2025

Cascading failures

Now in Spain we are thinking what happened to have a power outage. Integration points are usually the cause of this.

may 10 • 

Javi lopez

abril 2025

Dog-pile effect

The 28th of April in Spain, the whole country was under a power outage. The way the system was restarted, remembered me about the dog-pile…

abr 30 • 

Javi lopez

1

How to use Tech Debt for development?

You’ve probably heard this phrase, “We’ll refactor it later”, what do you feel with that?. Some people don’t trust this statement, so they…

abr 18 • 

Javi lopez

1

How does my mother cook?

When I ask my mother about the recipe to do anything she makes, her answer usually is just taste it and decide from that. Can we do the…

abr 5 • 

Javi lopez

marzo 2025

How much upfront design is enough?

Design is a word that we use to mention the abstract properties inherent to a product, in hardware this usually means to think in design…

mar 22 • 

Javi lopez

1

febrero 2025

Tests are closer to sacred cows than code

Change is the only constant in software, and we can change tests, but we should treat tests more as sacred cows than code. At the end, they…

feb 9 • 

Javi lopez

enero 2025

How to teach CI with “Little red riding hood”?

Let’s talk about the underlying idea of CI (continuous integration) and how to practice it, without the need of any dev knowledge.

ene 15 • 

Javi lopez

1