The power of regression testing in quality control

Imagine you are an architect building a skyscraper. You're trying really hard to align every beam and bolt with your goal. But a tremor occurs – a fault that is not immediately visible in the structure, but which increases with each new development. Ultimately, the masterpiece you created is on the verge of falling apart.

In software development, regression testing is equivalent to carrying out a complete inspection of the building to prevent this type of disaster from happening.

Let's delve deeper into what regression testing is and how it is used in modern software testing.

What is regression testing?

In essence, regression testing is the never-ending quest for stability. It involves re-running functional and non-functional tests to ensure that the complex network of code will continue to function without interruption after each modification, addition or extension made to the existing code base.

It is common for a code module to be affected by a change in another code module whenever the first code module is modified. The reason is the dependencies between the two. QA engineers perform a series of automated regression test cases after new logic or feature is added to the codebase. This prevents conflicts, saves time, maximizes testing efficiency, and most importantly, provides stability.

CISQ research found that poor software quality costs US businesses $2.08 trillion annually. Having mature testing methodologies, such as regression testing, is critical in software development.

Why regression testing is essential

Let's say you add a new feature and suddenly users can't log in. This is where regression testing comes into play. It prevents these types of disasters by detecting bugs early before they get worse.

Regression testing ensures that existing software functions have not been accidentally broken as an unintended byproduct of adding new features. It becomes increasingly crucial as software ages due to the growing repository of test cases from previous versions.

The main benefits of regression testing are:

• It detects defects in the early stages of development, preventing them from turning into larger problems.
• Helps preserve functionality after changes are made.
• Early fixes save companies time and money compared to resolving after release.
• It enhances user experience while maintaining reliability.
• Improves code adaptability and scalability.

Regression Testing Techniques

Regression testing is not a one-size-fits-all procedure. Different types of changes to code and contexts require custom regression testing tools and strategies. Let's take a look at some of the most common types.

Unitary Regression Tests

As the name suggests, unit regression testing analyzes specific functions or methods that make up the smallest parts of the software. These tests are important after changing a current function or adding new units to the code base.

Why drive them?

• They improve the reliability of code before it is integrated into the broader software ecosystem.
• The process becomes more agile.
• They facilitate documentation, speeding up the debugging process and making it more cost-effective.

Partial Regression Tests

Partial regression testing focuses on specific parts or modules of the software rather than examining the entire application. This approach is particularly effective when making small changes to various sections of the program or resolving bugs in specific modules.

Why drive them?

• They offer time efficiency compared to full regression testing.
• This method is ideal for software that consists of independent, well-defined modules.

Full regression testing

Full regression tests cover all features and capabilities of an application and are typically conducted on subsequent releases. These tests serve both as an interim evaluation after initial releases and as a final evaluation before the official release.

Why drive them?

• They provide a comprehensive assessment of software health.
• They also identify potential problems that may arise from dependencies between modules.

Progressive Regression Tests

Progressive regression testing is essential to verify that new modifications to a program do not impact existing functionalities. This method involves creating new test cases and is often used in automated regression testing. It is most relevant when you introduce new features to software or during regular iterative development stages.

Why drive them?

• They facilitate the seamless integration of new functionalities.
• This approach reduces testing duration by focusing on recent modifications.
• It ensures the stability of the current codebase.

Retest all regression tests

Retest regression testing involves re-examining all changes made to the application since its inception. This method provides the highest guarantee of software stability, especially after significant code reviews or modifications to fundamental software elements.

Why drive them?

• They provide the strongest safety net.
• This approach comprehensively checks for unexpected side effects in all areas of the software.

Corrective Regression Testing

Corrective regression testing primarily checks whether flaws in existing functionality identified in previous tests have been adequately corrected. This type of testing is typically conducted when no new functionality is added to the existing code base.

Why drive them?

• They are crucial to validating the effectiveness of fixes.
• They ensure that no new defects are introduced during the correction process.

Selective regression testing

Selective regression testing consists of choosing and executing a subset of test cases from a broader set of regression tests. This method is highly effective when there are time constraints and there is a need to test specific functionalities affected by recent changes.

Why drive them?

• They optimize resource usage and test coverage.
• This approach allows for personalized testing tailored to the specific nature of the changes.

Automated regression testing

As software applications become more complex and user-focused, manual testing methods are no longer adequate to ensure their quality. This is where automated testing comes into play.

Traditional manual testing methods often do not guarantee software quality. This gap is filled by automated regression testing.

Manual regression testing, typically performed after each update, verifies that existing functionality is not affected by new code changes. While effective, this method has limitations: it is labor-intensive, error-prone, and difficult to scale as software applications grow.

Why automate regression testing?

Automated regression testing, on the other hand, offers several important advantages:

Time efficiency: Automated testing significantly speeds up the testing process. This rapid execution allows development teams to receive immediate feedback on their code, enabling faster defect identification and resolution.

Consistency and Accuracy: Manual testing can be inconsistent, with human error leading to variability in both the testing process and results. Automated regression testing provides consistent results by performing the same steps accurately every time.

Scalability: As software applications grow, scaling manual testing development services efforts becomes increasingly difficult. Automated tests, on the other hand, can easily keep up with software expansion, maintaining complete coverage without requiring proportional increases in time or resources.

Integration with Continuous Integration/Continuous Delivery (CI/CD): Automated regression testing is particularly beneficial in CI/CD environments. These environments are characterized by frequent and rapid code changes, and automated testing ensures that each change is evaluated immediately and thoroughly, maintaining software integrity and performance.

How to perform regression testing

Regression testing is triggered based on any changes made to the software. It could be a bug fix, new feature integration, or something else entirely. Whenever this happens, the QA team performs the following activities.

#1 Test Planning

Goal Definition

First, it is essential to establish a clear goal for our testing process. This may involve identifying and resolving software bugs or ensuring that newly implemented code integrates seamlessly with the existing system. Having a well-defined objective will guide testing efforts in the right direction.

Scoping

Determining the breadth of testing is crucial. It's important to decide whether to perform a comprehensive analysis of the entire application or to focus specifically on areas affected by recent updates. Consulting change logs and release notes will be invaluable here because they shed light on the parts of the application that are most influenced by recent changes.

#2 Test selection

To ensure that the objectives are well defined, it is important to choose the tests from a set that will be performed at a given stage. To perform this task effectively, you will need a comprehensive understanding of software design.

#3 Test Prioritization

A recommended approach is criteria-based selection, where tests are prioritized based on the nature and impact of software changes. It is crucial to focus on high-risk areas and sections with a history of failures to detect any regressions.

Along with high-risk areas, you also need to consider business criticality and frequency of modifications. Sections that change frequently must be prioritized, and by business criticality we refer to features that are crucial for smooth business regulation.

#4 Test Design and Development

The test design component includes defining the number of tests to be performed, the methods that will be used to conduct the tests, and the circumstances of the test.

#5 Test Run

Next, it's time to run the tests. When tests need to be repeated and take a long time, automation tools can be very useful. They are more efficient while providing accuracy and stability.

There may be occasions when automatic scripts are not available. Or you may need to run exploratory tests. In these cases, manual testing is essential. Manual tests must have a thorough understanding of the application and have clear testing objectives for it to work well.

#6: Analytics and Reporting

After running the tests, you will review the results in detail. You need to carefully observe test case results to find and report bugs. Defects are then classified according to their severity and how quickly they need to be fixed.

#7 Feedback and Retest

Regression testing is not unique. It is an ongoing process that requires constant feedback. You will share findings with the development team so they can fix bugs. This is something that requires collaboration and problem solving from everyone involved.

#8 Test Maintenance

As the program evolves, the tests also need to evolve. It is crucial to evaluate the relevance of test cases to ensure their usefulness. Remove any obsolete test cases and introduce new tests that address the latest features. It's also important to update automation scripts because this ensures they are aligned with software changes.

Regression Testing Tools

When it comes to choosing a regression testing tool, there are several options. Here are some important considerations when choosing the right tool.

Nature of the Application

The complexity and nature of the application being tested plays an important role in selecting the right regression testing tool. For example:

Web applications: Tools like Selenium, Cypress or TestComplete are suitable for web-based applications because they can simulate cross-browser user interactions.

Mobile Applications: For application tools like Appium or Xamarin. UITests are generally preferred because they allow testing across devices and platforms. When it comes to testing desktop applications, tools like Ranorex or Telerik Test Studio are better suited because they offer features designed specifically for desktop environments.

Budget constraints

It's important to consider your limitations when selecting a tool. Some tools come with an exorbitant price tag, while others offer original or freemium models. Balancing your budget with the tool's desired features and capabilities is crucial.

Open source tools like Selenium can be cost-effective. They may require more effort to use compared to paid options like TestComplete or Ranorex, which provide comprehensive features for a cost.

Team skill level: Your team's familiarity and proficiency with different testing tools is important to ensure proper and effective use.

Programming languages: Some tools require knowledge of certain programming languages. For example, Selenium mainly uses Java, Python, C# and so on.

Ease of use: Evaluate whether the team can easily navigate to the interface and features of the tools. Introducing a tool can involve a learning curve that can initially impact productivity.

Integration Requirements

Consider the tool's compatibility and integration capabilities with tools or systems in your test environment. Here are some things to take into consideration:

1. CI/CD Integration: Make sure the tool you choose can be easily integrated into your continuous integration/continuous deployment (CI/CD) pipeline, such as Jenkins or GitLab CI.
2. Compatibility with testing frameworks: Make sure the tool works well with the testing frameworks or technologies your team uses. For example, if your team follows Behavior Driven Development (BDD), tools like Cucumber or SpecFlow could be beneficial due to their BDD support.

Let's take a look at the tools needed for regression testing.

Selenium

When it comes to browser-based and cross-platform regression testing tools, Selenium is one of the most popular open source solutions. As a free framework for automation testing, Selenium gives testers the ability to develop test scripts in any way they see fit. This is an appropriate solution for large-scale quality assurance teams that include experienced testers who have acquired skills and experience.

Benefits

• Offers browser compatibility testing.
• It supports multiple programming languages ​​like Java, C#, and Python and integration with CI/CD pipelines.
• It has robust community support with regular updates and features.

For industries that undergo continuous improvements and reviews, such as e-commerce or healthcare management, Selenium is the best choice for regression testing software.

At the same time, Selenium's steep learning curve is often a barrier for small or medium-sized teams. Furthermore, automated test scripts developed with Selenium need to be changed regularly to accommodate any changes that may occur in the code as it is a time-consuming process.

QTP (Professional Quick Test)

QTP is an icon-based tool for automated unit regression testing and functional testing. It assists testers in performing automated tests to find errors or gaps in the application being tested. It was initially designed by Mercury Interactive, which was later acquired by HP, and is now owned by MicroFocus.

QTP testing is based on VB scripting language and supports the largest set of software development environments such as SAP, Oracle and so on.

Benefits

• It supports recording and playback, providing ease of use with scriptless testing.
• Supports different add-ins like Oracle, Web Forms, Java, SAP, NET PeopleSoft, etc.
• It comes with comprehensive reporting and analysis.

In the real world, QTP can be employed to test mobile applications. It is also an excellent option for testing enterprise applications such as SAP, Oracle and PeopleSoft, where complex business processes need to be validated automatically.

Ranorex

Ranorex is another tool that provides test automation for software environments, devices, and applications. Similar to QTP, it offers regression and functional testing for desktop apps, web apps, and mobile apps.

Ranorex supports user interface technologies such as Java, HTML, C# Flash, Android, iOS and Silverlight. It even allows you to run tests and allows cross-platform testing. This means that test cases designed for Android can also be used for iOS testing.

Benefits

• It has a user interface for testers of all experience levels.
• It integrates seamlessly with tools and platforms.
• It provides detailed reporting and automated logging mechanisms.

With Ranorex, you can perform data-driven testing by parameterizing your test cases. For example, when testing your app's login functionality using this tool, you have the flexibility to test different usernames and passwords.

Test completed

TestComplete is an automated testing tool that serves a variety of application types and technologies. Developed by SmartBear Software, it is a complete solution for web applications as well as mobile and desktop applications.

Benefits

• TestComplete offers a testing method accessible to testers of various skill levels.
• It integrates seamlessly with popular CI/CD tools and version control systems.

TestComplete's flexibility makes it particularly effective for running automated regression tests. For example, you can create automation scripts that mimic users adding items to their shopping carts while shopping online. This ensures the accuracy of the product catalog and verifies that the correct items have been added to the cart.

Other tools

JUnit is a widely used open source testing framework for Java applications. Java developers use the framework to write automated tests that are rerun on each integration.

Next comes LoadRunner. While it is not just a regression testing tool, its performance and load testing capabilities can reveal vital information that informs regression testing efforts.

Lastly, Appium is another open source automation testing tool specifically designed for regression testing in mobile applications. It supports multiple programming languages ​​and offers cross-platform functionality, making it a versatile option.

Best practices for regression testing

Now that we've discussed software testing tools, techniques, and how to perform regression testing, let's look at some best practices. These practices will help you perform regression testing effectively.

#1: Keep test cases up to date

Digital solutions must be scalable and adaptable to keep up with the ever-changing technological landscape. Consequently, test cases must also be robust and scalable to maintain relevance and effectiveness.

Regularly updating test cases is crucial to avoid issues like false positives/negatives and to eliminate testing for obsolete features, which can cause confusion and unnecessary workload.

#2 Automate

Automated testing maintains consistency and reproducibility because it ensures that identical test cases are executed every time. This reduces the likelihood of making mistakes. Consequently, these tests can provide feedback on software programs more quickly than manual testing.

There are several automation tests available, each with its own personal set of functions. Tools like Selenium, JUnit, TestNG and others are some of the most popular.

#3: Prioritize test cases

First, prioritizing test case reuse involves creating test cases with usability in mind. By designing test cases that can be applied across projects, you can save time and effort.

Next, it's critical to focus on risk-based prioritization, which targets features or areas that are likely to have defects.

Lastly, aligning test case prioritization with business objectives is crucial. Keep user requirements and preferences (the business objective) in mind when determining the priority of test cases.

It's also important to involve developers, QA engineers, and business stakeholders in this step.

#4 Design Modular Test Cases

In some cases, written tests can be complex and difficult to follow. They can also take a long time. In this case, it is better to take an approach to test design by dividing functionality into test modules and developing tests for each specific function.

This approach promotes testing while ensuring consistency and reusability across test cases.

It not only provides convenience but also simplifies test cases by reducing their length and complexity.

A prime example of this is Netflix's approach to microservices architecture and modular testing, which helps reinforce the quality of the platform.

#5 Use version control

It's crucial to track test suite versions because knowing how and when a test case was modified helps put it in context. This helps you learn for the future and promotes collaboration among team members.

Git is a popular choice for code versioning because it allows you to revert to previous versions if you need to recover your data.

#6: Evaluate and remove outdated tests

Certain test cases can become outdated and irrelevant as software and testing practices evolve. This brings us back to the practice we discussed. Regularly reviewing the test suite reduces execution time, conserves resources, and minimizes the occurrence of positives and negatives.

Real Regression Testing Examples

Let's explore some real-life scenarios that illustrate the concept of regression testing.

E-commerce platform

Scenario: An Amazon-like e-commerce platform updates its website, introducing a feature that allows users to save items to their shopping carts. This change requires modifications to the website code.

Here, regression testing ensures that the new shopping cart feature works correctly and that existing functions such as adding, removing, and purchasing items remain unchanged. The goal is to identify any bugs or issues caused by the new code, including testing payment gateway integration, inventory accuracy, and compatibility across multiple devices and browsers.

Banking Software

Scenario: Banking software is being updated to improve user interface and security features, including updates to the authentication system and transaction encryption methods.

Regression testing is crucial to ensure that these updates do not compromise the security and fluidity of transactions. It verifies that customer data remains secure and that important functions like fund transfers, account balance checks, and bill payments work smoothly. These tests help identify security vulnerabilities and ensure compliance with established security standards.

Mobile apps

Scenario: An Instagram-like social media app releases an update with a new photo editing feature.

Regression testing ensures that this addition does not affect existing functionality such as posting photos, comments, or direct messages. It also checks application performance across different device models, operating systems, and network conditions. This process is vital to preserving a seamless user experience as you integrate new features.

Automotive Software Update

Scenario: An automobile manufacturer updates the vehicle's software to improve the driving capabilities and entertainment system.

Regression testing ensures that the update does not negatively impact vehicle safety and functionality. This test thoroughly examines new improvements and existing systems such as brakes, cruise control and safety sensors. It also ensures that the upgraded entertainment system integrates seamlessly without interrupting driving displays or causing distractions. The goal is to maintain safety and functionality while ensuring seamless operation within the vehicle's network of systems.

Conclusion

As part of a comprehensive QA testing strategy, effective regression testing is critical to ensuring that new and existing software features operate in harmony. By investing in meticulous planning and execution of regression testing strategies, companies can exercise greater control over their expenses, efforts, resources and time. This strategic approach contributes significantly to improving the quality of software products, highlighting the fundamental role of quality assurance testing in the development process.

Understanding regression testing types, following best practices, and using appropriate tools can help streamline the regression testing process. Therefore, if you consider skipping regression testing to meet deadlines, remember the importance of thorough preparation and its impact on the overall quality of the software.