7 Benefits of testing in isolation

This post originally appeared on The New Stack and is re-published here with permission.

Testing in isolation — testing individual components or modules separately from the rest of the system — can be expensive and time-consuming to execute thoroughly. It requires a testing environment, and sometimes multiple testing environments, along with detailed knowledge of your application and user expectations. That said, testing in isolation is important and effective.

In this article, we’ll examine seven benefits of testing in isolation. Along with these we’ll consider its drawbacks and costs. That way, you’ll be better informed when deciding to introduce isolation testing to your team’s DevOps environment.

Let’s explore how isolation testing solves local dependency issues, improves accuracy, promotes clean production, enables continuous deployment, locates tricky bugs, improves design and performance, and provides reference documentation.

Solving local dependency issues

Testing in isolation eliminates the “works on my machine” problem by finding hidden local dependencies that complicate deployment. Your development editor’s package manager integration — for example NuGet for .NET or Maven for Java apps — manages dependencies, but other factors like versioning add a management layer. By moving package management to the isolated testing environment, developers and testers guarantee that all testing uses the same dependencies.

Other local issues can include fixed drive mappings or other configuration settings files that might not match across different environments. When your team runs testing in an isolated setup, they avoid faulty configuration pointers.

Returning accurate results

Isolated testing provides a degree of scrutiny and accuracy that less-stringent testing methods can’t replicate. Developers get precise output verifications from discrete systems operating within the software.

DevOps engineers typically unit test each module in isolation. Instead of immediately testing the application workload as a whole, developers or testers unwrap and test each of the application’s modular units.

This unit testing achieves a high level of accuracy since it enables thorough testing and troubleshooting of any bugs. High accuracy is one of the best motivations for isolated testing. But, given the time and effort required, it can become a significant financial expense.

Promoting clean production

Investing in isolated testing can help you avoid more expensive cleanup caused by pushing bad code to production. It should be no surprise that bad code leads to later issues. So the earlier you validate and block faulty code, the better.

Remember how we mentioned that isolated testing is expensive? Well, pushing bad code to users hits you with an even more costs. Suppose your code leaves loopholes to bypass security, or data transactions go missing and result in data loss. You don’t want to lose a million-dollar payment transaction because you forgot to test your source code adequately.

Running isolated unit testing helps your team detect, fix and avoid these types of issues. It also allows developers focus on writing more solid code from the start. Your business will benefit as workloads run more reliably and bounce back from issues more easily.

Enabling continuous deployment

DevOps teams can run isolated testing as a stepping stone to continuous delivery and continuous deployment (CD). Pipelines are powerful step-by-step task sequences. Pipelines can automate almost every step of the deployment process, from building and compiling native source code, producing infrastructure-as-code templates to building containerized workloads. You can also integrate isolated testing as a part of your pipelines.

Isolated containerized testing ensures that code is always ready for immediate deployment and has the potential for automatic deployment. Another benefit is that you don’t have to change anything in your current DevOps pipelines processes. You just make isolated testing a vital component of a successful pipeline run.

Using continuous integration (the build stage) to validate and compile your source code and produce an artifact incorporating isolated testing makes the continuous deployment run smoother over all. This is because you’re able to do less troubleshooting and bug fixing.

Locating tricky bugs

Isolated containerized testing is a great way to tease apart a piece of software to find the source of hard-to-squash bugs. No matter when you write the tests — before, during, or after the coding process — isolated unit testing always finds bugs. In the long run, this saves you troubleshooting and maintenance efforts, ultimately reducing costs.

We’re not saying that isolated testing is the only way to detect bugs. Other testing types should also help bring these issues to the forefront. But by unwrapping each module of your application and running it through an isolated testing cycle, your team dramatically minimizes the chance of missing a bug.

Sometimes organizations use bug counts as a metric to measure code quality. In response, teams may try to hide these bugs rather than find and fix them. Testing in isolation reduces this risk, as the team tests each stand-alone unit on every level.

Improving design and performance

Isolated testing offers your team a chance to scrutinize every detail of your software, to improve its architecture, implementation, and performance. The previous benefit mainly focused on finding tricky bugs as a core part of the application’s source code. Here, we’re focused more on the overall system.

You may deploy the best available infrastructure architecture, aiming at high availability and resiliency. Yet this won’t help if the software is in a bad state. You should also consider validating performance and overall design improvements as part of your isolated testing scenarios.

For example, your application workload might run fine for a thousand concurrent users. Still, if more users connect to your workload, this can affect performance — or even worse, cause downtime. Running performance testing in isolation highlights system requirements and helps your team simulate different scenarios, from average use to unexpected peak use. This simulation identifies the impact on your application before disaster strikes.

Outages are expensive. When your team focuses time and effort on troubleshooting, they aren’t working on new features.

These outages can also harm your company’s reputation if your software is customer-facing. Imagine a finance or insurance organization with its core application down. That’s not the best way to convince customers of the organization’s reliability.

Providing documentation

Lastly, another benefit of isolated testing is that it provides a sort of working documentation. Going through detailed isolated unit testing requires testers or DevOps engineers to track testing and results, creating documentation you can use later as a reference.

For example, having documentation available on performing testing in isolation helps junior or new testing team members get up to speed quickly. It also helps scale and optimize the testing.

Of course, your team will need to keep documentation up to date whenever they integrate changes into the applications.

Conclusion

When you’ve been publishing application workloads to production without comprehensive testing, it may be a challenge to justify spending time and money on more thorough testing.

Although it costs more upfront, optimized isolated testing results in more reliable, more stable and secure, less buggy and better performing applications. Testing should save you money in the end.

Considering adding isolated testing to your DevOps efforts? CircleCI offers powerful tools to help you automate testing and ensure that each component of your application performs flawlessly before it reaches production. Sign up for a free CircleCI acount today to start building smarter and delivering faster, all while maintaining the high quality your users expect.