Regression Testing in Agile: What You Should Know About It

If you ask somebody about the most important stage of software development project realization, this person will likely name coding or design. However, we strongly believe that all the steps, including planning and software testing, are equally important, and their role in project realization can’t be underestimated. 

All the stages are like bricks and building a good “house” is impossible if at least one is absent. In this article, we’d like to discuss regression testing in Agile process, its methods, and possible challenges that a project team can face. 

Working as an Agile offshore software development company for more than 13 years, we accumulated knowledge that allows us to share our expertise and practical tips on building regression testing strategy in Agile. That’s why if you are interested in organizing your work processes following the principles of this methodology, this blog post will be of great use to you.

What Is Regression Testing in Agile?

The term “regression testing” is not always associated with Agile methodology. You can often hear it in the context of software development in general. 

One of the key aspects to decide on is the correct timing for running regression tests. Given the goals of this type of testing, it is conducted after developers have finished the process of building an app (or its features).

Agile Regression Testing: When to Conduct It

When is regression testing done in Agile? Is it sensible to do it only at the end of the development, directly before the product release? You should know that in the case of Agile, the situation is slightly different. Agile regression testing takes place at the end of each sprint. The critical aim that the team has when it conducts regression testing is to check the impact on the newly created functionality on the app. As a result, thanks to performing such tests, it is possible to ensure seamless functioning of the overall solution at any moment during the Agile development process.

Based on our practical experience, we can say that not every change introduced in the code will be a weighty reason for running the entire testing suite. Nevertheless, the common principle is straightforward: the more often your team runs the full suite, the easier and faster it will be to analyze the testing results, address any detected vulnerabilities, and fix bugs. 

Why is it so? Everything is quite simple. Thanks to frequent testing, you are more familiar with the entire code, the features of your solutions, and the way everything should work.

In general, we can define the following cases when running a full regression testing suite is required:

• After fixing bugs in the already existing functionality (it is vital to check whether bug-fixing activities haven’t led to new regressions);
• After building new functionality;
• After making software upgrades;
• Before deploying your code to production.

Why Is Regression Testing Important in Agile Development?

It is vital to ensure that after developers have introduced new features in the framework of a sprint, their previously built features are still functioning without being negatively impacted by all the changes. It doesn’t matter whether the sprint presupposes introducing serious updates or just some improvements to the already existing tools, as a rule, regression testing should be planned as an essential part of the development process within each iteration.

Due to the specificity of the Agile methodology, regression testing shouldn’t be a time-consuming process and that’s one of the reasons for the popularity of automated tests of this type. Usually, a sprint in Agile lasts for 2-4 weeks and during this time a team needs not only to build the required functionality but also to test the entire system, including the already existing features that were created for the previous releases.

If the development team ignores the necessity to conduct Agile regression testing, the results of their work can be rather disappointing as all the issues, bugs, and vulnerabilities will grow like a snowball with each new update. 

It is not enough to test each feature separately or their interaction. It is vital to see whether a new change introduced in the framework of the next sprint hasn’t affected those features and tools that have been created (and separately tested) earlier. 

You should be ready to face a situation when a small update seriously affects the functioning of the entire system. In such cases, only regression testing can help you to notice the problem and to address it timely and in a proper way.

Key benefits of conducting regression testing in Agile process:

• Wide test coverage. This type of testing is aimed at executing test cases for the entire functionality of your app at every stage of its development.
• The possibility of knowing about defects in advance. If the testing process is conducted properly and test results are analyzed correctly, the team will be aware of any defect in the software product beforehand. Thanks to this, it will be possible to resolve the problem timely.
• System stability. If the team conducts regression testing in Agile development while enriching an existing app with new features or fixing bugs in it, it is possible to ensure the stability of the functioning of the entire system. In other words, if you have a working app and need to expand it with new functionality or want to introduce some changes to it, thanks to regression testing, you will make sure that nothing will be broken after the introduction of these updates.
• Cost-efficiency. There are several points that demonstrate how regression testing helps you to optimize your expenses in Agile software development. First of all, regression tests can help you define and fix bugs that could lead to serious problems in the future, including financial and reputational losses. Secondly, it is possible to automate regression testing, which will allow you to reduce the testing team size and streamline the entire process.

Methods of Regression Testing in Agile Development

There can be several approaches to conducting Agile regression testing. The choice of the most appropriate method should depend on many factors, including but not limited to the type of your project, the number of experts who are responsible for conducting testing on your team, the size of the codebase, the time that you are ready to devote to regression tests, etc.

• Full re-testing. This approach presupposes that you will run all the tests that you have. Though somebody may decide that it will be a very good method that will help you to detect all the existing issues and re-check whether they haven’t appeared in some previously built parts of your software, it’s not really true. If you have well-written tests, they may help you to find regressions. Nevertheless, if the tests are imperfect, the risks that they won’t highlight the existing issues are rather significant. Moreover, this approach requires a lot of resources and if you have a large codebase, it will be not feasible to turn to this method.
• Selective re-testing. The principles of this method are based on the necessity to define a set of existing tests that are the most suitable for your codebase in its current state. It is necessary to identify those tests that will mainly focus on all (or at least practically all) parts of your codebase that were affected by the changes. However, it is important to understand that it is not always possible to select such tests. By making a wrong choice, you won’t be able to fully re-test all the existing functionality.
• Prioritized re-testing. It’s worth considering this method if you have a large codebase. In other cases, it may not be sensible to apply it. Careful testing of a big solution usually requires a lot of resources. To avoid such situations, teams can conduct prioritized tests. It means that they may choose those areas of code that are expected to contain bugs. That’s why in the first turn, they will conduct tests that will address these parts of software. After the successful running of these prioritized tests, the team can conduct the remaining ones.

Manual vs. Automated Regression Testing in Agile Environment

Another classification that can be used for identifying several methods of regression testing is based on the tools you will use for running tests. Here, we are going to talk about manual and automated testing.

Manual Testing

Manual testing will always be the basic approach to running regression tests regardless of the project management methodology that you prefer, and Agile is not an exception here. Manual tests should be applied before automated testing and often, they demonstrate even a higher level of efficiency in comparison to the second option. 

It is impossible to automate the process of regression testing without running manual tests first. That’s why at the earliest stages of the Agile development process, your team will fully rely on this type of testing. 

However, this approach also has its drawbacks. First, manual testing is a very time- and effort-consuming process. This disadvantage may not be very significant if you have just a small app. Nevertheless, when you have a complex software solution, your team won't have any possibility of conducting manual regression tests repeatedly. Otherwise, the process of building your app will be practically endless. That’s why today, project teams usually opt for applying automated regression tests in all situations when it is possible to do it.

Regression testing in Agile process presupposes regular repetitions, as every iteration will include tests of this type. Such tests help to detect possible issues (regressions) after the introduction of new functionality or bug fixing. But it is also vital to understand that relapses can appear in other situations, for example, due to security or performance problems or because of using an updated browser version. It means that testing requires a pretty complex approach that will unite various cases and combinations.

Automated Testing

To facilitate routine processes for a team, it is recommended to introduce automation that will cover repeatable and stable cases. The team will have more time and possibilities to concentrate on manual tests of the most complicated cases thanks to automated tests.

However, while building a regression testing strategy in Agile, you shouldn’t try to automate all test cases (let’s be honest, full automation in this case will be not only impossible but also useless). The main task for you will be to define the right combination of manual and automated tests to ensure the highest efficiency for you.

There are some key points that we recommend you bear in mind while planning automated regression testing in Agile environment.

• Project size. We advise our clients to rely on automation in those cases when they have medium and large projects, especially those that require testing solutions with different subsystems. Nevertheless, if you have a short-term project that presupposes building just a small app (or a separate functionality for an existing solution), it will not be the best idea to invest in test automation. In the majority of such cases, it will be not only cheaper but also faster to conduct manual tests. 
• Manual testing as an initial point. When you have a feature that is still being developed, writing automated regression tests against it is not recommended. You should understand that it may be just a waste of time as it is highly likely that the feature will change and your automated tests will turn out to be useless. That’s why manual testing should be conducted at least once so that you will already have results that you can compare with the results of automated testing in the future.
• No 100% automation. Do not try to replace all manual tests with automated ones. Depending on the peculiarities of your project, automated test cases should cover nearly 70%-90% of manual repeatable tests. If you try to achieve 100% automation coverage, 10%-30% of these tests may be ineffective (report false positives or negatives or only isolate bugs), and all the allocated resources will be wasted.

Possible issues related to Agile regression testing automation:

• Lack of information about the product. Very often, specialists responsible for testing face such situations when there is practically no product-related documentation and business scope remains unclear. We should admit that in Agile software development, supporting proper documentation and its regular updates can become quite a challenging task, given the specificity of this methodology. However, testers need to be aware of all the ongoing changes and the most recent requirements for preparing automated regression test cases. Otherwise, test cases may turn out to be ineffective and irrelevant.
• Regular updates. Your automated regression tests should fully reflect all the changes introduced to your software product under development. By regularly adjusting test cases to the ongoing state of your solution and its functionality, you can ensure the highest quality and accuracy of the testing process. 
• False positives and false negatives. Sometimes it happens that the testing results demonstrate that your product has issues while there aren’t any of them and, vice versa, tests can verify that everything is perfect while it is not. Several reasons can cause it. For example, tests can be improperly coded or designed or become obsolete and irrelevant in the ongoing situation.
• Choice of the right tools. Selecting the most appropriate tools for testing automation may become a challenge. Today, there are a lot of various options provided by different vendors. All of them have pros and cons, and it is vital to choose the best variants for the type of software you are building.

Possible Challenges of Regression Testing in Agile Development

When talking about Agile regression testing, it is also essential to mention some of the most common pitfalls and challenges your development team can face while performing such activities. When well-informed about possible issues, you can get fully ready to address them. Otherwise, they can become a severe barrier to conducting efficient and smooth tests and ensuring the desired quality of your solution. That’s why we highly recommend you consider them in advance.

• Introduction of multiple changes. One of the strongest sides of Agile and the benefits of this methodology for businesses is the possibility of introducing changes and updating requirements after the start of the development process. Without any doubt, thanks to this flexibility, companies can build efficient software solutions that will be tailored to all their ongoing needs. However, while some changes can be insignificant from the development perspective, others can significantly disrupt the entire iteration. It may become a serious problem if you conduct automated regression testing in Agile environment. While automation is aimed at facilitating and streamlining processes for the team, such changes become a serious obstacle.
• Growing scale of regression testing. The scale of regression tests is gradually increasing with each next iteration because you need to test the entire solution that you are expanding at each new sprint. As a result, with regression testing Agile teams need to allocate more and more resources and time to check the functioning of the entire system. Manual regression tests can become practically unmanageable after a couple of sprints. To cope with this situation, teams need to introduce automated tests. At the same time, they need to frequently review and update them to remove those tests that aren’t helpful.
• No possibility of using record-and-playback testing tools. Record-and-playback tests are among the methods of automated testing. Such tools allow you to record the activity that was performed by a user and then re-run it. In this case, there is no need for any manual intervention. These tools can significantly help a team, but the problem is that for Agile projects, such tools can’t be used at the initial steps of development. At the same time, the functionality is still not ready for employing such tools, but it is already required to start conducting regression testing.
• Need for communication. Agile regression testing best practices should always include regular, close, and result-oriented communication between developers, business analysts, QA engineers, and stakeholders. Thanks to efficient interaction, ensuring an excellent understanding of the product concept and all the already introduced and undergoing changes is possible. With this knowledge, experts responsible for preparing automated tests will be able to optimize the testing process and remove those tests that are no longer required due to the updates.
• Maintenance of test cases. To better verify the quality of the functionality of your solution, it is recommended to expand the range of automated test cases. Nevertheless, the more test cases you have, the more effort will be required to maintain them. It is necessary to ensure that your test cases are not too rigid and not loosely coupled with the functionality of your solution. Otherwise, in the first case, you will need to update and rewrite them even after the smallest change is introduced to the system. And in the latter case, such tests won’t be able to detect a lot of issues.

How to Build a Regression Testing Strategy in Agile

To ensure that regression testing will be smooth, the team responsible for running tests should develop a sound strategy before proceeding directly to development. 

As we’ve already mentioned, Agile provides a lot of flexibility to all stakeholders and participants of the project realization. That's why the team should also be ready to modify the approved strategy before each sprint cycle. 

We always recommend including smoke and sanctify tests as the essential steps of the regression testing plan. Smoke tests will help you to see whether the built functionality is appropriate for the following stages of testing. If such tests demonstrate that it is not stable enough to be tested, it will be required to strengthen the system before moving further. Sanity tests aim to verify whether the chosen components are functioning as they are supposed to after fixing bugs and introducing changes.

What should you remember while building a regression testing strategy?

Our key tips:

1. Prioritize test cases. The most important points should be targeted at those components and areas more likely to fail. Your app may have such details that will yield even after the most minor updates or changes, and you should pay special attention to them.
2. Your regression test cases should cover all scenarios that are possible. Only in this case you can be sure that you will be able to detect and fix all the bugs. Otherwise, you won’t be able to define problematic areas and properly address them. Just remember: your goal is to detect all the issues before users can do it.
3. Check tests for correctness. Do not forget to check the correctness of regression test scripts and modify them for every new iteration.
4. Establish close interaction in a team. Establish close communication between developers, specialists responsible for testing, and product owners. Without regular and direct interaction supported by all stakeholders, your testing team will have serious difficulties understanding what changes have been introduced, how new features should work, and what areas should be monitored with special attention.
5. Ask the stakeholders to review test cases that your team prepares regularly. It should be done to ensure the highest quality and efficiency of test scripts. The stakeholders will help you to define whether nothing has been missed for testing the functionality following the relevant requirements.
6. Create a traceability matrix (or ask the testing team to do it). This matrix will help map the test cases and the existing and regularly updated requirements for software. As a result, thanks to this, the team can be sure that all business requirements will be covered by testing and nothing will be occasionally skipped.
7. Concentrate on risk areas. During regression testing, concentrate on risk areas of the solution that negatively impact the overall quality of the solution.
8. Defects report analysis. Deeply analyze defect reports generated by testing automation tools after each test cycle execution. Such statements will help you better understand the most problematic areas and the progress achieved during the latest iteration compared to the previous ones.
9. Always create detailed documentation for the testing process. In this documentation, it is required to describe your regression test plan. You need to mention the scope of testing, the used approach and methods, tools, techniques, schedule, entry/exit testing criteria, available resources, etc.

How to Сhoose the Right Team for Agile Regression Testing?

As a rule, when a company plans to build a software solution, there are several options like relying on in-house developers, establishing cooperation with freelancers, or working with an onshore, nearshore, or offshore dedicated development team. Of course, thanks to the flexibility of business models, you also have other options, including projects-based outsourcing, staff augmentation, and various hybrid models. Your choice should be based precisely on your situation, ongoing business conditions, your plans, goals, budget, etc.

You can hire external specialists for all the services related to the process of building your custom solution or only for some separate functions like Agile regression testing. It means that such tasks as planning, design, and product development will be the tasks of your in-house team. At the same time, the chosen vendor will provide QA services and will be responsible for writing test cases, running manual tests, preparing scripts for automated testing, etc.

The choice of a company for such services doesn’t seriously differ from hiring a team that will build a software product from scratch. You need to analyze the company’s expertise in your business domain, experience in Agile development and testing, and the financial side of your future cooperation. It will be a good idea to study the company's portfolio and ask questions about cases that the company has worked with and that are similar to yours. It is always better to work with specialists who already know how everything should be organized and how to achieve the highest efficiency of regression testing in Agile development.

The costs of the testing team’s services may become a crucial factor for your business, but we recommend you choose a company with reasonable rates (too low rates should be an alarming sign for you!).

Closing Word

At Geomotiv, we strongly believe that testing in general and regression testing in particular, is a highly important stage of any software development process, especially when discussing Agile methodology. Every iteration should be accompanied by running tests to avoid a lot of issues in the future when all the features of your product are already built.

Agile regression testing is more complex than development teams expect but with the right approach, you can ensure excellent effectiveness of all your efforts aimed at testing your solution.

All our developers, designers, QA engineers, and other experts involved in development have rich expertise in working on Agile projects and deeply understand the peculiarities of this methodology. If you rely on us in building and testing your custom solutions, we can guarantee the best results and the highest efficiency of our work.