Building software has become more and more complex compared to just a few years ago. The number of moving parts required to run a modern application seems to increase with every passing year. The tools to build an application have multiplied, you'll interact with multiple APIs internally and from third parties, the infrastructure needs are more significant, and so on. Because of this ever-expanding complexity, it's becoming more challenging for developers and testers to test these applications.

Another consequence caused by this complexity is the interconnectivity between all segments of an application. It's almost impossible for any developer to have a deep understanding of how everything interacts with each other under the hood. A change in one module or service can have unknown consequences on a seemingly unrelated part of the product. If the team is lucky, they'll spot it quickly and fix it before it goes into production. More often than not, though, those defects remain undiscovered for weeks or months—usually by an upset customer who ran into the problem before the team did.

Throughout my career, I've seen first-hand how disruptive these unexpected bugs can become. I recently experienced this while working on a project as a freelancer. When I joined the project, I didn't have much knowledge of the entire scope of the project. In my first week, I made what seemed like a small, harmless change to the codebase. A senior developer on the team approved and merged it. What we didn't know is that my change caused a separate batch reporting job to fail silently. The team didn't discover the problem with the job until my change went into production three weeks later, and it took a whole day for someone to find out that my tiny change was the culprit.

The team had encountered many similar issues, so they graciously empathized with my embarrassing mistake. Still, I was more disappointed that neither I nor the team caught the problem earlier and made it easier—and much cheaper—to fix. If something is functioning in an application, developers and testers should ensure that it remains functional throughout all the changes that happen daily. That's why regression testing is an essential part of the software development lifecycle.

What Is Regression Testing?

Regression testing is a type of testing for software applications that validates the existing functionality of the software to ensure it performs in the same way after changes. It covers both functional testing (how the application is supposed to work) and non-functional testing (how the application is supposed to behave). The goal of regression tests is to confirm a new change hasn't introduced a new bug or broken something that worked.

At a high level, teams do regression testing by running a predetermined set of test scenarios against the updated application, verifying that those scenarios still work as intended. The regression tests typically include sections of core functionality or high business value, areas directly affected by the new changes, and previously failed scenarios. Many testing teams conduct this testing manually, going through a checklist or script of existing functional sections of the application and confirming that the new changes work as intended.

This process, like most other software development testing processes, helps maintain the quality of an application over time. Going back to my previous story, regression testing could have helped us detect that my code change broke the reporting job. Unfortunately, at the time of my blunder, the team didn't have any formal processes for this kind of testing. If someone explicitly validated the reporting job before shipping the updates to production, the team could have detected the problem sooner and patched the code in minutes instead of a full day.

The Challenges of Manual Regression Testing

Manual regression testing presents many obstacles that might cause teams to avoid them despite the benefits of verifying current functionality after each change in the system. The following are a few common issues teams face when performing these kinds of tests manually.

Manual regression testing is time-consuming

The primary reason many companies don't do regression testing, especially smaller startups, is because it takes too much time. Depending on the size and scope of your application, it can take significant effort to complete a full round of regression tests. For many organizations juggling multiple priorities, they can't or won't allocate the time needed to do a deep dive to keep quality high.

For example, one company I worked with managed a reasonably large web application with a ton of complex business logic under the hood. To go through the entire application, the QA team dedicated a whole week solely for regression testing before any significant release to production. Even worse, if the team found critical bugs in areas of high business value during the process, they would have to start over again, even if it happened on the last day. As you might expect, this approach led to countless delays.

Manual regression testing might require tons of resources

As the saying goes, time is our most precious commodity, and manual regression testing can drain much of it. But this type of testing also consumes other resources, especially staff and infrastructure. You have testers from the QA department doing the bulk of the work, but it can also involve different roles. For instance, developers might spend hours fixing issues found during testing, or ops teams need to provision testing environments before QA can begin. The additional support required for regression testing often takes teams by surprise.

For smaller organizations, the main problem is the lack of resources to do a decent job at regression testing. Most startups I work with don't have dedicated testers on staff or can't spare the time and money needed to prepare a proper space for testing purposes. Because of these shortages, these teams often use inadequate cobbled-up systems and pull someone from another department, like customer support or design, to do testing whenever they have some spare time. It leads to a dip in quality since the staff and the testing environment aren't well-suited for the task.

Manual regression testing is prone to human error

For most, doing manual testing is an exercise of mind-numbing repetitive work that takes far too much time. After filling out the same forms and clicking the same buttons for what seems like the thousandth time, we'll likely skip a step or two in the process that allows some bugs to sneak in. Most of the time, we accidentally mix up test scenarios that go through the same sections of the application. Sometimes, we do it intentionally—we've all taken shortcuts when pressed for time or bored out of our minds.

Usually, this problem is caused by combining the previous two problems with manual regression testing mentioned above. When an organization doesn't have the time, people or infrastructure needed to do an excellent job at these tests, people rush through their testing or must deal with subpar systems to accomplish their work. Whatever the reason, it causes a noticeable dip in quality over time.

Why Automation Is Critical for Regression Testing

Given all the drawbacks of performing the slow and repetitive steps required for regression testing, teams should explore alternatives to alleviate this bottleneck. Imagine having a consistent and repeatable process that takes minutes to complete while involving fewer people. That's what automation can do to the regression testing process. It's a critical component for resolving the obstacles that block software development teams from delivering high-quality work quickly.

Leveraging automation lets you deal with the issues mentioned above. No matter how fast a tester is, a computer can go through the same steps of a test scenario in a fraction of the time. Computers also follow instructions well and won't take shortcuts, making test runs more reliable than when someone rushes through them. Finally, once the team properly sets up the automated test suite in your systems, it won't require human interaction to run all of your project's regression tests. It's a win-win scenario for everyone involved, from developers to testers to the eventual users of the product.

No matter how challenging it may seem to automate regression tests, it usually yields enormous benefits for an organization. A real-world example is the company mentioned earlier that required an entire week to run its regression tests. The team spent a few months automating most of their testing process. The result of their efforts was going from one week for regression testing to under two hours for validating the same coverage. Their capacity for developing and delivering new features to their customers grew exponentially and led to a spike in growth and revenue for their product.

Automation Is Great, but It's Not a Silver Bullet

For most organizations, automation sounds like the perfect solution to all their testing woes. They think that they can use automation to eliminate tests that take far too long and require far too many resources. While automated tests relieve the bulk of testing woes for teams, they bring unique challenges that can create new problems for developers and testers.

Long-term maintenance of automated tests is a necessity

One of the most common mistakes teams make with test automation is thinking that once they automate a scenario for their application, they don't need to touch it again. Unfortunately, maintaining automated tests is something that all teams need to deal with regularly. Someone needs to keep the tests working when the application under test changes its functionality, or the underlying architecture modifies how the system behaves. These updates don't come for free.

In a sense, maintaining an automated test suite involves more effort than supporting manual testing documents or scripts. For manual testing, the tester usually only needs to update the spec in a document. For automated tests, someone needs to modify them alongside the code updates, which adds an additional layer of work for any new commits to the codebase. While this ensures that tests also serve as living documentation of the current state of the application, it can become challenging for startups and smaller teams that make frequent changes.

Automated tests can slow the team down if not done right

Building an automated test suite often starts smoothly. Your team creates a few test cases that run in seconds, never failing unless new changes to the application cause them to fail. Over time, as the team continues changing the codebase and building the test suite, you may notice the automated tests don't run as quickly as before. Occasionally, a test or two begins to fail for no reason, only to pass on the next try. Before you know it, the team is dealing with a bulky, unreliable automated test suite that's creating more work and slowing everyone to a crawl—the opposite of what automation should help with.

Many organizations start their automation journeys without paying attention to how these seemingly minor issues can snowball into more significant problems down the road. I've seen teams abandon their automation testing efforts because it got out of control quickly. As an automated test suite expands, so will all the moving parts required to keep them running smoothly. This additional complexity elevates the chance of failure, which can compound over time if not addressed in a timely manner.

You can't automate all of your regression tests instantly

Automation can cover a lot of testing scenarios, but it can't cover everything easily, whether due to technical complexity or because it's not feasible. Most applications these days interact with multiple systems, both internal and external, complicating the various paths needed for validation. It makes automating certain functionality almost impossible unless the team is willing to invest a lot of time and money to build and maintain automation for these sections.

For instance, let's say you're working on a web application that uses a third-party payment processor. The payment processor has a sandbox for testing, which your automated tests can use to simulate successful and unsuccessful payments. But your application also relies on receiving a webhook after a successful payment, which isn't guaranteed to arrive in a specific time frame. You have no control over the webhook delivery, so you must mock this behavior for your automation, which adds something else the testing team has to maintain. In cases like these, it's a better choice to do manual testing if validating actual behavior is required.

Choosing the Right Tools for Automated Regression Testing

If you're starting your automated regression testing journey, you'll have to consider which tools to use for the process. The automated testing market is full of various test automation tooling for all needs. It might feel a bit overwhelming at first to decide where you'll want to invest your time and money with all the available options, but with some guidelines, you'll find the right equipment for the job. Here are a few tips to help you find the right tools for your team.

Think about your available in-house expertise

It would help if you first considered who will use the automated testing tools to build out your test suite when searching for the right tools for automating your regression tests. Will the person or team responsible for creating the automated test suite have the knowledge and experience to accomplish this task while keeping long-term maintenance in mind? The answer to this question will help narrow down your choices.

For instance, if developers are primarily responsible for generating automated tests, you can leverage their coding experience to use libraries and frameworks in the programming languages or ecosystems they use for the application and where they're most comfortable. For testers who don't have coding skills yet, consider using codeless tools to help ease them into the world of test automation.

Figure out what systems you will automate

Automated testing tools exist for different kinds of applications, from desktop to web to mobile. Your decision on a testing tool will depend on which type of applications your organization currently manages or will manage in the near future. If your company only has a mobile application with no plans to expand beyond it, look for testing tools with a strong focus on mobile device testing. For organizations that maintain web and desktop applications, a multi-purpose tool that covers both will serve you best. An excellent choice for this is Telerik Test Studio, which will have your regression tests covered for the web and desktop.

It's essential to take the time to research which tools will work best for your existing needs as well as potential future changes. It might be tempting to focus only on tools that can test different kinds of applications. However, it's often better to use the ones best suited for your applications as they'll have better functionality to help with your test scenarios. Think of it as using a hammer for a screw—you can brute-force your way into putting in the screw with the hammer, but it'll be more effective if you use a screwdriver instead.

Evaluate immediate and future costs

You can find automated testing tools for your regression tests with costs that range from free to thousands of dollars. Unfortunately, the immediate cost of a tool doesn't necessarily reflect its quality. Some free testing tools rival the functionality of their much pricier counterparts, and some of the expensive tools don't have all your team needs to create practical automated regression tests.

The allure of using free, open-source testing tools sounds attractive. However, don't think that adopting these free solutions costs nothing. While it doesn't incur immediate costs, free tools can become more expensive in the long run. With open-source tools, you're on your own when you need support. Your team will have to spend hours or days chasing solutions on online forums or YouTube that may or may not work. Your team should keep these direct and indirect costs in mind when deciding on a tool.

Keys to Successful Automated Regression Testing

Like other software development practices, making automated regression testing successful for your organization takes time and effort. You might be able to whip up a quick test suite that helps in the short term. Without proper care, however, those tests will become a burden on your team. If you plan to keep automated regression tests around your application for the long haul, the following tips will help keep them running smoothly.

Maintain your tests and what runs them

This article mentions maintenance multiple times and with good reason. It's tempting to add more and more tests without taking care of existing ones, but it's one of the worst mistakes you can make. Over time, slowness and brittleness can make it nearly impossible to create or modify tests without negatively affecting the entire system. Every automated test suite can become a clunky, slow mess without frequent and intentional upkeep.

Make sure your team carves out time to maintain the automated regression tests regularly and include it as part of their testing duties. Refactoring the code that runs the tests can make them more efficient to execute and more effortless for other team members to understand. Another tip is to do periodic reviews of your existing test scenarios and prune any test scenarios that no longer serve your needs. You can also update the tools and libraries that power your automation to gain significant improvements. These small efforts pay off big time.

Make it easier for anyone to run the tests

Many teams build automated regression test suites without figuring out who will or should execute them. Often, a single person or team runs the tests at the end of a development cycle or sprint, which can contain dozens or hundreds of changes, making it difficult to track down any regressions that occur. Sometimes, there are technical challenges where the tests require seemingly arcane commands to work. Both of these situations reduce the value of automating these tests in the first place since the barrier to entry is too high.

The solution to these problems is to make tests easy for anyone to run at any time. For instance, if your tests need specific infrastructure, look into virtualization to allow the team to spin up what they need on demand. Ideally, development and testing teams would work together to build these systems and document what's required. Using standardized tooling and clear documentation that explains how the automated regression tests work will eliminate any potential obstacles for the rest of the team.

Run your regressions tests as often as possible

No matter how easy it is to execute your automated regression tests, the truth is that very few people will run them frequently on their own. This issue is especially true if the automation takes a long time to go through since these interruptions will cause people to break their workflow. Context switching between coding and running tests has a real cost in productivity. However, the longer you wait to run your regression tests, the longer it takes to uncover and fix any issues arising from a change.

The key to resolving this issue is continuous integration—the practice of frequently merging and automatically testing new code to ensure that your systems remain stable through all modifications. Every time a developer commits an update to your application's codebase, a continuous integration system runs your automated regression tests, creating a rapid feedback loop that enables your team to address problems before they escalate or slip through the cracks. This practice will make the most out of your test suite.

Final Thoughts: Automated Regression Testing Is Vital for High-Quality Software

In this age of rapid development cycles, frequent deployments and high expectations from stakeholders and companies alike, testing is at the forefront of these efforts. Regression testing serves to ensure the existing functionality of an application doesn't break and to maintain a high level of quality and consistency. However, the process of manual regression testing can take a significant chunk of time to complete, requires plenty of resources and is susceptible to errors.

Automation resolves the issues of running regression tests by hand, making the process more effective and efficient. Automated regression tests have their unique set of challenges, however, and require a strategic approach that goes beyond simply automating manual tasks. Teams building these test suites must make them maintainable and easy to use, as well as execute them early and often. By making regression tests a routine part of the software development lifecycle, you're not just attempting to catch bugs—you're also fostering a culture of quality throughout your organization.

This article was originally published on the Telerik blog.