July 26, 2017

...Learn TDD with Codemanship

Gold Standard Teams do Continuous Inspection

Working with so many dev teams across a diverse range of industries gives me a great insight into the common features of teams that consistently do great work.

I call these the Gold Standard development teams. And they write gold standard code.

Gold standard code, to me, is code that maybe only 1% of teams are writing. It's more reliable and more maintainable than 99% of the code I see.

Importantly, Gold Standard dev teams don't usually take any longer to deliver working software than their Silver and Bronze Standard peers. Often, they deliver sooner. And it's no coincidence. The practices that lead to gold standard code also tend to make earlier and more frequent delivery easier.

One common feature I see in Gold Standard dev teams is that they do continuous inspection of their code to ensure that it's of a high quality.

Some teams review code quality once in a blue moon. Some review code in every iteration. Some review code with every check in.

Gold Standard dev teams review code quality as often as they test their code, every few minutes. This means they pick up code quality "bugs" almost as soon as they're introduced.

Like functional bugs, code quality bugs are much easier to fix the sooner they're caught. Catching issues immediately enables Gold Standard dev teams to produce very high quality code at little to no extra cost. Often, it saves time.

Continuous testing of software requires a high level of test automation. It's not really possible any other way. Continuous code inspection is no different. Rigorously examining the code for a multitude of problems every few minutes is extremely difficult to do by eye alone. Pre-check-in reviews, and even pair programming, are not enough.

Luckily, there's an ever-growing supply of tools we can use to automate our code inspections. Unsurprisingly, demand for the specialist skillset required is growing rapidly, too.

What kind of questions should we ask in our continuous code inspections? To some extent, that will depend on your specific code quality goals. But there are themes that are common to most code:

1. Complexity - How much "stuff" is there in our code? How many lines of code in this function or module? How many branches? How many operators and operands?

Gold Standard dev teams know the price of increasing code entropy, and fight it vigorously. Is this method getting a bit big? Let's split it into a composed method. Is this class doing too much? Let's split it into multiple classes that each have one distinct job.

2. Duplication - When we duplicate code - and concepts - we end up having to maintain the same logic in multiple places, multiplying the cost of making changes to it.

Gold Standard dev teams monitor the code closely for similarities. Are these two blocks of code kind of the same? Let's turn it into one parameterised method. Are these two classes sort of doing the same thing? Maybe extract the common elements into their own class and have both of them reuse that.

3. Dependencies - If we change a line of code in one place, how much of the rest of the code will break? Unmanaged dependencies - couplings - in our code can amplify the "ripple effect" and multiply the cost of even the smallest changes.

Gold Standard teams are continually aware of, and constantly managing, the dependencies in their code. When a class depends too much on other classes, they reshape the code and redistribute the responsibilities to localise the impact of change.

They also make sure that as many of their dependencies as possible are swappable: that is, one function or class or component can be easily swapped with a different implementation with no impact on the calling code.

4. Readability - Code that's difficult to understand is difficult to change without breaking it.

You may be thinking that it's not possible to automate the checking of code readability, and to some extent that's true. But studies have shown a very strong correlation between the complexity of code and how easy it is to read and understand. For example, code that has a lower Maintainability Index tends to score lower for readability, too.

As well as monitoring code for complexity, Gold Standard dev teams can also monitor the semantic content of their code using an increasingly sophisticated array of Natural Language Processing tools.

Simple applications of well-established readability metrics, like Flesch Reading Ease, can also help draw our attention to difficult code.

And even something as simple as calculating the conceptual correlation between names in our code and words used by our customers to describe the problem domain can help highlight code that may not be "speaking the customer's language".

5. Test assurance - If we made a change that broke the code, how soon would we know? How easy would it be to pinpoint the problem?

This is a crucial factor in the cost of changing code, and one that's usually overlooked in discussions about maintainability. Bugs cost exponentially more to fix the later they're discovered. The goal of automated regression tests is to discover them sooner, which saves us a lot of time.

Gold Standard teams continuously monitor how good their automated tests are at catching regressions. The way they do this is to deliberately introduce errors into their code, and see if any of the tests catch them. This is called mutation testing, and there are tools available for many programming languages that will do it automatically, alerting devs to any gaps in their automated test suites and giving them increased confidence when making changes.

Another key component of test assurance is how often we can run our automated tests. The longer they take to run, the less often we can run them and the longer we have to wait for feedback. Gold Standard teams monitor test execution time and optimise their test suites to run as fast as they need.

And finally, when a test does fail, Gold Standard teams are able to pinpoint the problem and fix it sooner, because their tests typically ask less questions. A Gold Standard automated test suite might cover 100,000 lines of production code with 10-20,000 tests, each having only one reason to fail. LOC/test is a key metric for Gold Standard teams, and they rarely let it go beyond 10 LOC/test.

PS. Shameless plug: If you'd like to learn more about Continuous Inspection, I run a bite-sized training workshop on code craft metrics.

Posted 3 weeks, 4 days ago on July 26, 2017