Automation has a lot of potential to improve software development. Unfortunately, though, automation is often seen as a luxury. Deadlines in the real word are unforgiving, and since test code isn’t product code, automation tasks are given lower priority and dunked into the black hole of the backlog. Some might argue that this is okay because it is lean or because a new project is just getting started. Once, I even heard it quipped that the first ones cut during a layoff are the automation folks. And it is true that automation requires a nontrivial resource investment.
However, I want to turn the tables. Instead of thinking about automation in terms of the opportunity, think about automation in terms of the opportunity cost. What happens if you don’t automate your tests from the get-go? There are 10 major things you lose:
#1: Man Hours
Automated tests will automatically run. Manual tests must be manually run. That’s ontological. If you only run a test one time, then automation has no return-on-investment. But if you run a test more than once, automation saves a tester from repeating themselves. Plus, it’s easy: push the button and wait for results. Automated tests almost always run faster than manual tests, too. Considering that time is money and engineer salaries aren’t cheap, man hours are a clear opportunity cost.
Automated tests can achieve greater coverage than manual tests, particularly for regression testing. As product development progresses, the sheer number of test cases increases. For example, in Agile, new tests will be created every sprint. Older tests must be run periodically to verify that new features don’t break existing features. If regression tests are manual, then testers must burn hours grinding through the same tests repeatedly. Often, for expediency, this means that they skip some tests – not in the sense of being lazy, but rather as part of a risk-based approach. Weaker coverage plus risk of missing bugs are accepted for the sake of shorter testing time. If those regression tests were automated, then there would be no reason to shrink coverage, because they would be easy to run.
People make mistakes. It’s human nature – nobody’s perfect. And manual tests are prone to human error because humans run them. I remember how nervous I felt running manual on-call system checks at MaxPoint for the first time, afraid that I would miss a problem that could bring down a million-dollar bidding system. Automated scripts run the same way every time.
Continuous integration (CI) protects code against defects by building and testing every code change in real time. A CI system will automatically trigger tests all the time.Tests not running in CI (like manual tests) are effectively dead. At NetApp, failing code changes would immediately be kicked out of the code line, making automated tests act like a vaccine against bugs. On the other hand, I remember a project at MaxPoint that was riddled with bugs and perpetually delayed. When I asked the developers to see their unit tests, they said they never wrote unit tests because “it wasn’t a requirement.”
#5: Delivery Time
Continuous delivery (CD) is the natural extension of continuous integration, in which software products can automatically be delivered (and potentially even deployed) as the final step in a CI pipeline. This is how big companies like Google, Facebook, and Netflix can deliver so rapidly. No automation means no CD.
#6: Results and Metrics
Non-engineers (managers, product owners, scrum masters, oh my!) love to ask questions about tests. “Are we red or green?” “How many tests do we have for this feature?” “What’s our coverage?” “How often do we run the tests?” Automated tests simply yield more accurate and more comprehensive results. Automation can also generate test reports, so engineers don’t need to waste time drafting emails or updating wiki pages.
Numbers don’t lie. Scripts don’t lie. Engineers typically don’t lie, but… results from manual tests can have a fudge factor, or a mistake in reporting, or any other sort of inconsistency. Inaccurate results may lead to poor business decisions. Automated results tell it like it is.
Manual testing can devolve into repetitive, menial labor: just follow steps 1-10 again and again and again. It would be much more effective for manual testers to focus on exploratory testing rather than deterministic testing. While automated tests can cover the fixed, repetitive test scenarios, exploratory testing lets testers find creative ways to uncover defects and judge how well a product actually works. Lack of automation ties up human capital.
#9: Peace of Mind
Are you sure that your product is “good”? Can you run enough tests to make sure? I learned the value of peace of mind while I was still in college. In my compiler theory course, I had to develop a simple programming language and build a compiler for it. Every week, we had to add new language features: arithmetic, strings, arrays, functions, etc. And every week, I wrote a slew of mini-programs to test grammar updates to my new language. By the time the project was complete, I had 1000+ automated test cases running through JUnit with 100% coverage, and the entire suite took a mere few minutes to run. And there were many late nights when the tests caught bugs in my language right away before committing code. There was no way I could have passed that class without my automated tests.
The ultimate purpose of test automation is product quality. Having automation doesn’t necessarily mean product quality is good, but not having automation severely limits how quality can be pursued. Anecdotally, I’ve seen much better code quality come out of projects that have good test automation than ones without it. If I were a product owner, I know what I would want.