Imagine you’re an architect building a skyscraper. You’re putting in so much effort to align each beam and bolt with your goal. But a tremor occurs—a flaw that’s not immediately visible in the structure but grows wider with each new development. Ultimately, the masterpiece you’ve created is on the verge of falling apart.
In software development, regression testing is the equivalent of performing a thorough building inspection to prevent this kind of disaster from happening.
Let’s delve deeper into what regression testing is and how it’s used in modern software testing.
What is Regression Testing?
In essence, regression testing is the relentless pursuit of stability. It involves rerunning both functional and non-functional tests to guarantee that the complex web of code will continue to function without any interruptions after each modification, addition, or extension made to the existing codebase.
It’s common for one code module to be affected by a change to 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 a new logic or feature is added to the codebase. This is to prevent conflicts, save time, maximize test efficiency, and, most importantly, provide stability.
CISQ research finds that poor software quality costs US companies $2.08 trillion yearly. Having mature testing methodologies like regression testing in place 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 catching bugs early before they escalate.
Regression testing ensures that existing software functions have not been accidentally damaged as an unintended by-product of adding new features. It becomes increasingly crucial as software ages due to the expanding repository of test cases from previous releases.
The main benefits of regression testing are:
- It catches defects in the early stages of development, preventing them from snowballing into bigger issues.
- It helps preserve functionalities after changes are made.
- Early fixes save businesses time and money compared to addressing them after release.
- It enhances the user experience by maintaining reliability.
- It improves the code adaptability and scalability.
Regression Testing Techniques
Regression testing is not a one-size-fits-all procedure. Different types of changes in code and contexts demand tailored regression testing tools and strategies. Let’s take a look at some of the most common types.
Unit Regression Tests
As the name suggests, unit regression tests look at particular functions or methods that make up the smallest parts of software. These tests are important after changing a current function or adding new units to the codebase.
Why Conduct Them?
- They enhance the code’s reliability before it integrates into the broader software ecosystem.
- The process becomes more agile.
- They facilitate easier documentation, streamlining the debugging process and making it more cost-effective.
Partial Regression Tests
Partial regression tests focus on specific parts or modules of the software rather than examining the entire application. This approach is particularly effective when making minor changes in various sections of the program or addressing bugs in specific modules.
Why Conduct Them?
- They offer time efficiency compared to full regression testing.
- This method is ideal for software that consists of well-defined, independent modules.
Full Regression Tests
Full regression tests cover all features and capabilities of an application and are typically conducted throughout subsequent releases. These tests serve as both an intermediate evaluation after initial releases and a final assessment before the official launch.
Why Conduct Them?
- They provide a comprehensive assessment of the software’s health.
- They also identify potential issues that might arise from dependencies between modules.
Progressive Regression Tests
Progressive regression testing is essential for verifying that new modifications in a program don’t impact existing functionalities. This method involves creating new test cases and is often used in automated regression testing. It’s most relevant when you’re introducing new features to software or during regular stages of iterative development.
Why Conduct Them?
- They facilitate the seamless integration of new functionalities.
- This approach reduces test durations 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 in the application since its inception. This method provides the highest assurance of software stability, particularly after significant code overhauls or modifications to the software’s foundational elements.
Why Conduct Them?
- They provide the most robust safety net.
- This approach comprehensively checks for unexpected side effects in all areas of the software.
Corrective Regression Tests
Corrective regression testing primarily verifies that flaws in existing functionalities identified in earlier tests have been properly fixed. This type of testing is typically conducted when no new functionalities are added to the existing codebase.
Why Conduct Them?
- They are crucial for validating the effectiveness of fixes.
- They ensure that no new defects are introduced during the correction process.
Selective Regression Tests
Selective regression tests consist of choosing and running a subset of test cases from a broader regression test suite. This method is highly effective when time constraints exist and there’s a need to test specific functionalities affected by recent changes.
Why Conduct Them?
- They optimize resource usage and test coverage.
- This approach allows for customized 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 fall short of ensuring software quality. This gap is filled by automated regression testing.
Manual regression testing, typically conducted after each update, checks that existing functionalities remain unaffected by new code changes. While effective, this method has limitations: it’s labor-intensive, error-prone, and challenging to scale with the growth of software applications.
Why Automate Regression Testing?
Automated regression testing, on the other hand, offers several key advantages:
Efficiency in Time: Automated tests significantly speed up the testing process. This rapid execution allows development teams to receive prompt feedback on their code, enabling quicker identification and resolution of defects.
Consistency and Accuracy: Manual testing can be inconsistent, with human error leading to variability in both the testing process and the outcomes. Automated regression testing provides consistent results by executing the same steps precisely every time.
Scalability: As software applications grow, scaling manual testing efforts becomes increasingly difficult. Automated testing, in contrast, can easily keep pace with expanding software, maintaining thorough 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 promptly and thoroughly evaluated, maintaining the software’s integrity and performance.
How to Perform Regression Testing
Regression testing is triggered based on any change done to the software. It can be a bug fix, new feature integration, or something else entirely. Whenever this happens, the QA team performs the following activities.
#1 Test Planning
Objective Setting
First, it’s essential to establish a clear goal for our testing process. This could involve identifying and resolving software bugs or ensuring that newly implemented code seamlessly integrates with the existing system. Having a well-defined objective will steer testing efforts in the right direction.
Scope Definition
Determining the breadth of the testing is crucial. It’s important to decide whether to conduct a comprehensive examination of the entire application or to concentrate 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 suite that will be conducted at a particular stage. In order to effectively accomplish this task, you’ll need a comprehensive understanding of the software’s design.
#3 Test Prioritization
A recommended approach is criteria-based selection, where testing is 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 faults to catch any regressions.
Along with high-risk areas, you also need to consider business criticality and frequency of modifications. Sections that often change should be prioritized, and by business criticality, we refer to functionalities crucial for smooth business regulation.
#4 Test Design & Development
The test design component includes defining the number of tests to be carried out, the methods that will be utilized to conduct testing, and the test circumstances.
#5 Test Execution
Next, it’s time to execute the tests. When tests need to be repeated and take a long time, automation tools can prove to be very helpful. They’re more efficient while providing accuracy and stability.
There may be occasions when automatic scripts aren’t available. Or, you might need to run exploratory tests. In these instances, manual testing is essential. Manual tests must have a thorough understanding of the app and have clear test goals for it to work well.
#6 Analysis & Reporting
After the tests run, you’ll review the results thoroughly. You need to carefully look at the outcomes of test cases to find and report bugs. Then, defects are ranked by how bad and quickly they need to be fixed.
#7 Feedback & Retesting
Regression testing isn’t a one-off. It’s an ongoing process that requires constant feedback. You’ll share findings with the development team so that they can fix the 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’s crucial to assess 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 that they align with the software changes.
Tools for Regression Testing
When it comes to choosing a regression testing tool, there are several options. Here are some key considerations when choosing the right tool.
Nature of the Application
The complexity and nature of the application being tested play a 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 user interactions across browsers.
Mobile Applications: For app tools like Appium or Xamarin. UITests are usually preferred because they allow for testing on devices and platforms. When it comes to testing desktop applications, tools like Ranorex or Telerik Test Studio are more suitable because they offer features specifically designed for desktop environments.
Budget Constraints
It is important to consider your limitations when selecting a tool. Some tools come with a steep price tag, while others offer source or freemium models. Balancing your budget with the desired features and capabilities of the tool is crucial.
Open source tools like Selenium can be cost-effective. These may require more effort to use compared to paid options such as TestComplete or Ranorex, which provide comprehensive features at a cost.
Team Skill Level: Your team’s familiarity and proficiency with different testing tools are important for ensure proper and effective usage.
Programming Languages: Some tools require expertise in certain programming languages. For example, Selenium primarily uses Java, Python, C#, and so on.
User Friendliness: Evaluate whether the team can easily navigate to the interface and functionalities of the tools. Introducing a tool might involve a learning curve that could initially impact productivity.
Integration Requirements
Take into account the compatibility and integration capabilities of the tool with tools or systems in your testing environment. Here are a few things to take into account:
- Integration with CI/CD: Make sure the tool you choose can smoothly integrate with your Continuous Integration/Continuous Deployment (CI/CD) pipeline, like Jenkins or GitLab CI.
- Compatibility with Testing Frameworks: Verify that 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. Because it is a free framework for automation testing, Selenium gives testers the ability to develop test scripts in any way that they see fit. This is an appropriate solution for large-scale quality assurance teams that include experienced testers who have acquired both skills and experience.
Benefits
- It 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 resources.
For industries that undergo continuous enhancements and overhauls like e-commerce or healthcare management, Selenium is the top pick for regression testing software.
At the same time, Selenium’s steep learning curve is typically a barrier for teams that are small or medium-size. Additionally, automated testing scripts developed with Selenium need to be regularly altered in order to accommodate any changes that may occur in the code because it is a time-consuming process.
QTP (Quick Test Professional)
The QTP is an icon-based tool for automated unit regression testing and functional testing. It assists testers in carrying out automated tests to find any errors or gaps in the application being tested. It was initially conceived by Mercury Interactive, which was subsequently purchased by HP, and is now owned by MicroFocus.
QTP Testing is based on the scripting language VB script and supports the largest pool of software development environments like SAP, Oracle, and so on.
Benefits
- It supports record and playback, thus providing ease of use with scriptless testing.
- It supports different add-ins like Oracle, Web Forms, Java, SAP, NET PeopleSoft, etc.
- It comes with comprehensive reports and analytics.
In the real world, QTP can be employed for testing mobile applications. It’s also an excellent choice 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 environments, devices, and software applications. Similar to QTP, it offers regression and functional testing for desktop apps, web applications, and mobile apps.
Ranorex supports user interface technologies such as Java, HTML, C# Flash, Android, iOS, and Silverlight. It even allows the execution of tests and enables cross-platform testing. This means that test cases designed for Android can also be utilized for iOS testing.
Benefits
- It boasts a user interface for testers of all experience levels.
- It seamlessly integrates 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 the login functionality of your application using this tool, you have the flexibility to try different usernames and passwords.
TestComplete
TestComplete is an automated testing tool that caters to a range of application types and technologies. Developed by SmartBear Software, it is an all-in-one solution for web applications, such as well as mobile and desktop apps.
Benefits
- TestComplete offers a testing method that is accessible to testers of various skill levels.
- It seamlessly integrates with known CI/CD tools and version control systems.
TestComplete’s flexibility makes it particularly effective for executing automated regression tests. For instance, 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 are 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 re-executed on each integration.
Next comes LoadRunner. While it’s not purely a regression testing tool, its performance and load testing prowess can uncover vital information that informs regression testing efforts.
Lastly, Appium is another open-source automation testing tool specifically designed for regression testing on mobile applications. It supports various programming languages and offers cross-platform functionality, making it a versatile option.
Best Practices for Regression Testing
Now that we’ve discussed tools, software testing techniques, and how to perform regression testing, let’s look at some best practices. These practices will assist you in performing regression testing effectively.
#1 Keep Test Cases Updated
Digital solutions must be scalable and adaptable to keep pace with the ever-changing tech landscape. Consequently, test cases should 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 tests for deprecated features, which can cause confusion and unnecessary workload.
#2 Automate
Automated tests maintain consistency and reproducibility because they ensure that identical test cases are run every time. This reduces the probability of making mistakes. Hence, these tests can offer feedback on software programs more quickly than manual testing does..
There are several automation tests available, each with its own personal set of functions. Tools such as Selenium, JUnit, TestNG, and others are some of the most popular.
#3 Prioritize Test Cases
First and foremost, prioritizing the reusability of test cases involves creating test cases with usability in mind. By designing test cases that can be applied across projects, you can save both time and effort.
Next, it is essential to focus on risk-based prioritization, which aims at functionalities or areas with a probability of defects.
Lastly, aligning test case prioritization with business goals is crucial. Keep user requirements and preferences—the business goal—in mind while 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 challenging to follow. They can also take a lot of time. In this case, it’s best to adopt an approach for test design by dividing functionality into test modules and developing tests for each specific function.
This approach promotes testing while ensuring consistency and reusability in test cases.
Not only does it offer convenience, but it 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 bolster the platform’s quality.
#5 Utilize Version Control
It is crucial to keep track of versions of test suites because knowing how and when a test case was modified helps you put it into 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 back to previous versions if you need to recover your data.
#6 Evaluate and Remove Outdated Tests
Certain test cases may 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-life Examples of Regression Testing
Let’s explore some real-life scenarios that illustrate the concept of regression testing.
E-commerce Platform
Scenario: An e-commerce platform similar to Amazon updates its website, introducing a feature that lets users save items in their shopping cart. This change requires modifications to the website’s code.
Here, regression testing ensures the new shopping cart feature works correctly and that existing functions, like adding, removing, and purchasing items, remain unaffected. The goal is to identify any bugs or issues caused by the new code, including testing payment gateway integration, inventory accuracy, and compatibility across various devices and browsers.
Banking Software
Scenario: Banking software is being updated to enhance the user interface and security features, including updates to the authentication system and transaction encryption methods.
Regression testing is crucial to ensure these updates do not compromise security and transaction smoothness. It verifies that customer data remains secure and that key functions like fund transfers, account balance checks, and bill payments function seamlessly. This testing helps identify security vulnerabilities and ensure compliance with established security standards.
Mobile Apps
Scenario: A social media app similar to Instagram releases an update with a new photo editing feature.
Regression testing ensures this addition doesn’t affect existing functionalities like photo posting, commenting, or direct messaging. It also checks the app’s performance across different device models, operating systems, and network conditions. This process is vital to preserve a seamless user experience while you’re integrating new features.
Automotive Software Update
Scenario: An automobile manufacturer updates vehicle software to improve driving features and the entertainment system.
Regression testing ensures the update does not negatively impact vehicle safety and functionality. This testing comprehensively examines both the new enhancements and existing systems, such as brakes, cruise control, and safety sensors. It also ensures the updated entertainment system integrates smoothly without disrupting driving displays or causing distractions. The goal is to maintain safety and functionality, ensuring seamless operation within the vehicle’s system network.
Conclusion
As part of a comprehensive QA testing strategy, effective regression testing is instrumental in ensuring that existing and new 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 significantly contributes to enhancing software product quality, underlining the pivotal role of QA testing in the development process.
Understanding the types of regression testing, following best practices, and using the appropriate tools can help streamline the regression testing process. So, if you consider skipping regression testing to meet deadlines, remember the importance of thorough preparation and its impact on overall software quality.
