If you could only do one thing to make better software, what would it be?

Good technical practices are what we have to do to make good software – this is the engineering part of software engineering. Design. Coding. Testing and Reviews.

If you could do only one thing to make better software, what would it be? Where would you get the most bang for your buck?

Continuous Integration – Making Code Run

Continuous Integration is an obvious place to start. You need to build the software and get it running before you can do anything useful with it.

Getting developers to check in and sync up with each other more often. Building the system more often – at least once a day to start, then on every check in. Which means simplifying and automating the steps to build the system. Making sure that the system builds successfully every time – without errors or warnings. Which means that people can run it and try it out whenever they want. Make sure that it will run correctly. Which means adding tests and checks as part of the build and deploy steps. Building information radiators so that everyone knows the status of the build and when the build is broken.

You can’t be Agile without Continuous Integration, and you need Continuous Integration in place before you can go down the Devops path to Continuous Delivery or Continuous Deployment.

And Continuous Integration works in sequential Waterfall delivery too. Developers in these environments might check in more code less often, but there is still real value in knowing that you can build and run the system and see it working sooner rather than later, especially in big enterprise systems and big programs where getting dependencies worked out and all the pieces working together is a huge challenge.

Developers testing their own work – Making Code Work

Making developers responsible for testing their own work, automating this as much as possible by building on Continuous Integration, is the only way to deliver software faster and keep costs down – depending too much on manual testing and hand-offs to a test team will slow you down too much.

Almost every organization that I have talked to over the past couple of years is pushing more responsibilities for testing onto developers, and pushing more testers into development teams (or out of the organization altogether), following the lead of Google and now Microsoft, to become "more Agile".

This means relying more on developers to write good automated tests (unit tests, basic UI regression using Selenium or Watir) and static analysis checking in Continuous Integration or the developer’s IDE to find common coding mistakes and security vulnerabilities.

But there are limits to what developers will catch in their testing, even good developers. Once you get developers to write tests (before, or after they write the code, it doesn't matter, now that TDD is dead), you’ll end up with mostly simple unit tests or UI regression tests that don’t stray far from the happy path, proving that the code does what the developer thinks it is supposed to do – because that is what they need to get their work done. Their assumptions and blind spots will be reflected in the tests as well as the code. Little or no negative testing. Or usability testing. Or security testing. Or stress testing. Or system-level integration testing. All of which still has to be done by somebody - unless you expect your customers to find your bugs for you.

It will take a long time before the team learns how to write good, efficient tests, and before they build up a set of tests that will catch real bugs, rather than just getting in the way. But if you do this right, you can deliver good code while still moving fast, and get better value out of testing.

Code Reviews or Pairing – Making Code Good

Another way to get better code is by getting developers to do code reviews.

Code reviews should be about finding problems in the code first – checking for correctness, defensive coding protection (error handling and API contracts and thread safety and data validation), security (using security libraries correctly for access control and output encoding, protecting confidential data, logging and auditing…). And about making the code better – more understandable, safer and easier to change.

Code reviews are expensive, so do them right: lightweight, risk-based, using static analysis first to catch low-level mistakes and bad coding practices so that reviewers can spend their time looking for more important problems.

Instead of code reviews, you could try pairing as a way to get another pair of eyes on the code.

Pairing isn’t the same as reviews – the goals and priorities are different. A good reviewer will find problems even in code developed through pair programming, because reviewers look for different things. But research proves that disciplined pair programming will give you better structured, cleaner code, with fewer bugs. And pairing is a much better way to teach programmers about the system than code reviews are.

The downsides of pair programming? The cost of having two people do the work of one person – a good pair will work faster than one person on their own, but the less experienced or less skilled team member will slow the pair down to what they can deal with. Focus fatigue. Pairing can be exhausting, which means people can’t do it for too long at a stretch, before their work becomes superficial or strained. And social problems. People who like it, like it a lot. But people who don’t like it won’t do it at all.

Refactoring – Making Code – and Design – Last

What about design? Collaborative design workshops? Design reviews? Threat modeling in design to take care of security and operational risks?

We do all of these things. But as we continue to iterate through the design and as our code base grows, refactoring – to retain, and sometimes restore, the design, and to keep the code maintainable – is becoming more and more important.

It’s easy to learn your IDE’s refactoring tools and the basic ideas behind refactoring. But it’s not easy to learn how do refactoring right (although you can learn a lot in a short time from Woody Zuill and Llewellyn Falco in their “2 Minutes to Better Code” video). Understanding why some refactoring approaches are better than others. How to save time refactoring. How to do it safely.

Mariusz Sieraczkiewicz does a good job of explaining how and when to do "everyday refactoring" using a matrix built on Michael Feathers’ work on brutal refactoring and the biology of code:

1. Start by reading and annotating the code, maybe do some scratch (rapid, throwaway) refactoring to understand it better
2. Find meaningful names for variables and conditionals
3. Extract methods to break down big chunks of code and express the algorithm
4. Get rid of obvious duplication
5. Move methods and extract classes to isolate responsibilities.

I agree with Sieraczkiewicz that these simple steps “would heal most code bases on this planet”. He then goes on to describe larger and more fundamental “strategic refactoring” (aka “root canal refactoring"): refactoring to patterns, introducing new architectural constructs. Work that carries much higher risks and costs. This is where refactoring ends, and re-design and re-architecture starts.

What would you do, to make Better Software?

Continuous Integration can pay off quickly: the change in transparency and in the team’s focus is almost immediate.

Developer testing is a journey, not a goal. It will take a long time for most developers to get good at it, and a long time to build up a good set of tests that you can rely on. The sooner you start, the better.

Code reviews can also take a long time to pay off. Developers – and managers – need to make the time for reviews to be done and build the discipline, and developers need time to learn how to review code properly, and how to give and accept criticism. But code reviews – or pairing – will give you better code.

Refactoring is more of a compounding investment – you pay a little bit today to save a lot in the future.

If there is only one thing that you could do to make better software, what would it be? Where would you start?