Mobile apps face frequent updates and OS-level changes. Regression testing on real devices ensures that previous functionalities still work flawlessly across screen sizes and OS versions.

1. Optimizing Regression Testing
in a DevOps Pipeline

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Software development is an ever-evolving, dynamic process. Although
unit tests are crucial for confirming that individual code components
are valid, they frequently fail to protect the overall behavior of the
program. Regression testing becomes an essential safety measure in
this situation.
Regression testing is a procedure used in quality assurance that aims
to stop new code modifications from breaking current features.
Software applications can be routinely retested after updates to help
detect and fix unintended repercussions that might jeopardize system
stability and user experience. Regression testing serves as a watchful
guardian, making sure that your program keeps functioning as
intended even as it develops and expands.
Modern teams also rely on visual regression testing to ensure that
changes in code don’t unintentionally affect the user interface or
layout. This is especially important in responsive design and
cross-platform environments, where visual accuracy is as critical as
functionality.
What is Regression Testing?
Regression testing is a type of software testing that verifies whether
the pretested and developed software still functions efficiently and
effectively after being modified or interfaced with another feature or
software. The importance of the regression test is to verify that the

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newly applied source code changes will not affect the previously
existing functionalities.
Regression testing is used whenever the code changes: for
enhancement, after patches, or configuration updates. It can include
re-running past test cases, checking if the software’s behavior remains
consistent, and comparing current behavior with previous versions.
For software, regression testing is a primary factor in maintaining
long-term quality and reliability.
Why is Regression Testing
Important?
Regression testing is a critical part of the software development
process. It helps to ensure that changes made to the software do not
negatively impact existing features. This is important for several
reasons:
●​ To maintain software quality: Regression testing helps to ensure
that the software is of high quality and meets the needs of users.
By identifying and fixing defects early in the development
process, regression testing can help to prevent costly problems
from occurring later on.
●​ To reduce the risk of defects: Regression testing can help to
reduce the risk of defects being introduced into the software. By
testing the software after each update, regression testing can

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help to identify and fix any defects that may have been
introduced.
●​ To improve software reliability: Regression testing can help to
improve the reliability of the software. By testing the software
under a variety of conditions, regression testing can help to
identify and fix any defects that may cause the software to fail.
●​ To save time and money: Regression testing can help to save
time and money by preventing defects from being found later in
the development process. By identifying and fixing defects early
on, regression testing can help to reduce the cost of fixing
defects later on.
Types of Regression Testing
Regression testing can be categorized into several types to ensure
software quality and reliability by verifying that new changes do not
adversely affect the existing functionality. Here are some common
types of regression testing:
●​ Corrective Regression Testing: Corrective regression testing is
one of the simpler forms of regression tests and requires
minimal effort. This type of testing is used when no changes are
introduced to the existing code while adding new functionality to
the application, but the system is tested to ensure it works as
intended. The primary focus is testing the existing functionality
and executing the existing test cases without creating new ones.
●​ Selective Regression Testing: Selective regression testing
evaluates the impact of both new and existing code changes on
an application. It involves incorporating common elements, such

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as variables and functions, into the application to quickly identify
results without disrupting the overall process.
●​ Retest-all Regression Testing: Retest-all regression testing
involves re-testing all test cases to ensure that code changes
have not introduced any new bugs in the application. It is
time-consuming and is generally avoided unless the application
is relatively small, as this type of testing requires significant
effort from the QA team.
●​ Progressive Regression Testing: Progressive regression testing
is used when there are changes in the software’s existing code.
Test cases for a progressive regression test are created based
on specific requirements. When there are only minor product
improvements, new test cases are designed to ensure that they
do not affect the existing code of the product.
●​ Complete Regression Testing: Complete regression testing
involves re-testing the entire application when there are
significant multiple modifications to the current code and helps
to identify and address any issues introduced during the testing
process.
●​ Partial Regression Testing: Partial regression testing is
performed when new code is added to an existing codebase.
This method helps identify critical bugs in the existing code and
ensures they are tested without disrupting the overall system.
●​ Unit Regression Testing: Unit regression testing is a key
component of regression testing, where the code is tested in
isolation. During this process, all other interactions, integrations,
and dependencies are disabled, focusing on the smallest
testable parts of an application (units). This type of testing is
usually conducted during low-traffic periods and off-peak hours.

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When to perform Regression
Testing?
Regression testing is essential whenever changes are made to the
software’s codebase. This includes:
●​ New Feature Development: Introducing new functionalities, such
as adding Facebook login to an existing email-based login
system, can impact existing features. Regression testing
ensures these features continue to operate correctly.
●​ Functionality Removal: Eliminating features, like removing
“Remember Password,” requires regression testing to verify that
other parts of the application are unaffected.
●​ Bug Fixes: Correcting defects, such as fixing a broken login
button, necessitates regression testing to prevent unintended
consequences.
●​ Performance Improvements: Optimizations, like reducing
homepage load time, can introduce new issues. Regression
testing helps identify and address these.
●​ Environment Changes: Modifying the application’s environment,
such as switching databases from MySQL to Oracle, demands
regression testing to confirm compatibility and data integrity.
●​ Long Development Cycles: For large-scale projects, regression
testing is crucial to maintain software quality over extended
periods. Frequent testing, such as daily or weekly, is
recommended to catch issues early.

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In essence, any alteration to the software, regardless of its scale,
warrants regression testing to protect existing functionalities and
ensure overall system stability.
How to perform Regression
Testing?
While specific regression testing strategies can vary across
organizations, a common framework underlies these approaches.
Let’s break down the essential steps involved:
1. Identify Changes​
The process begins by pinpointing modifications to the codebase.
This includes new features, bug fixes, performance enhancements, or
environmental changes. Understanding the scope of alterations is
crucial for effective test case selection.
2. Test Case Prioritization​
Not all test cases are created equal. Prioritizing test cases based on
their criticality to the application is essential. Focus on test cases that
cover core functionalities, high-risk areas, and frequently used
features. This optimization ensures efficient test execution and
resource allocation.
3. Test Estimation​
Accurately estimating the time required to execute the regression test
suite is vital for project planning. This step involves analyzing the

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number and complexity of test cases, available resources, and testing
environment factors.
4. Test Case Categorization​
Deciding which test cases to automate and which to execute manually
is a strategic decision. Typically, repetitive, time-consuming, and
high-frequency test cases are prime candidates for automation.
Manual testing is often reserved for exploratory testing, user interface
verification, and complex scenarios.
5. Test Execution​
The final phase involves executing the prioritized test cases according
to the chosen approach (manual or automated). Test results are
meticulously analyzed to identify any defects or regressions
introduced by the code changes.
By following these steps, organizations can establish a robust
regression testing process that safeguards software quality and
prevents unexpected issues from arising.
Tools for Regression Testing
Here are some popular regression test tools that can be useful for
creating and executing tests. Each tool comes with its key advantages
and disadvantages. However, it is important to thoroughly study your
requirements before deciding which tools to use.

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1. TestGrid​
TestGrid is a comprehensive test automation platform that offers a
range of features for efficient regression testing. Its key features
include:
●​ Visual Regression Testing
●​ Cross-Browser and Device Testing
●​ Integration with Automation Frameworks
●​ Real-time Reporting and Analytics
●​ Collaboration and Accessibility
2. Selenium​
Selenium is an industry-standard open-source tool primarily used for
automating web applications. Its key feature is its ability to support
multiple browsers (Chrome, Firefox, Safari, etc.) and operating
systems, making it highly versatile for cross-platform testing.
Additionally, Selenium offers a robust framework for creating complex
test suites, including data-driven and keyword-driven testing
approaches.
3. Playwright​
Playwright is a relatively new open-source tool that has gained
popularity due to its speed, reliability, and cross-browser compatibility.
It supports multiple programming languages (JavaScript, Python,
.NET, Java) and provides features like auto-waiting, asynchronous
execution, and parallel testing. Playwright is particularly well-suited for
modern web applications that utilize asynchronous programming.
4. Puppeteer​
Another open-source tool, Puppeteer is specifically designed for
controlling Chrome or Chromium-based browsers programmatically.

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It’s primarily used for Node.js environments and offers features like
generating screenshots and PDFs, simulating user input, and
intercepting network requests. While it’s primarily focused on web
scraping and automation, it can also be used for regression testing.
5. Appium​
Appium is an open-source tool specifically designed for automating
native, hybrid, and web mobile applications. It supports both iOS and
Android platforms and uses the WebDriver protocol, making it
compatible with Selenium test scripts. Appium’s key feature is its
ability to test mobile apps on real devices, simulators, or emulators.
Benefits of Regression Testing
The benefits of regression testing are substantial and extend across
various aspects of software development. By consistently executing
regression tests, organizations can significantly enhance software
quality, reduce risks, and improve overall efficiency.
●​ Improved Software Quality: Regression testing helps identify
defects early in the development cycle, preventing them from
reaching production and impacting end-users. This leads to a
more stable and reliable product.
●​ Risk Mitigation: By verifying that existing functionalities remain
intact after code changes, regression testing helps mitigate the
risk of introducing new defects or exacerbating existing ones.
●​ Cost Reduction: Early defect detection through regression
testing can save significant costs by preventing issues from
escalating into more complex problems.

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●​ Increased Customer Satisfaction: A high-quality product with
minimal defects directly contributes to enhanced customer
satisfaction and loyalty.
●​ Faster Time-to-Market: Efficient regression testing processes
can accelerate the software development lifecycle by reducing
testing time and increasing confidence in releases.
●​ Enhanced Test Coverage: Regression tests complement other
testing types, expanding test coverage and ensuring
comprehensive quality assessment.
●​ Supports Agile Development: Regression testing aligns well with
Agile methodologies by providing continuous feedback on code
changes and enabling rapid iterations.
Challenges in Regression
Testing
Regression testing plays a crucial role in identifying bugs while
introducing new features or updates to an existing codebase. It helps
mitigate app crashes and performance bottlenecks. However,
software testers and developers face several challenges when running
regression tests, some of which include:
●​ Test Suite Cost and Time: Whenever new features are deployed,
there is a requirement for continuous improvement of a
regression test suite. As a result, the number of test cases
fluctuates, necessitating the re-running of new and old tests,

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which can be time-consuming. Implementing parallel testing can
be an effective solution, as it allows test cases to run
●​ Maintenance: With the growth of the application, the complexity
of test cases in regression test suites also increases. Hence,
proper maintenance is essential to manage this complexity and
optimize execution time. concurrently across multiple browsers
and operating systems, significantly reducing lead time.
●​ Complex Test Cases: As the project or application grows, both
the number and complexity of test cases increase, consuming
substantial time and resources.
Best Practices for Regression
Testing
Regression testing helps in checking whether a developed and tested
software application functions effectively after there are changes in
the code or interfacing with other software. Below are listed a few
best practices that help in efficient functioning through regression
testing:
●​ Automate Regression Tests: Automation helps save a lot of time
and assures consistency in the testing process. Automated tests
should run frequently and quickly to ensure that the new
changes do not break existing functionalities.
●​ Prioritize Test Cases: Test cases must be prioritized based on
critical functionality and the impact of recent changes is done as

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all the test cases written are not very important. This helps in
testing the most critical parts of the application to test first.
●​ Maintain Test Scripts: Keep updating and maintaining the test
scripts with each change to the application. This way, tests will
remain current and effective in detecting regression.
Conclusion
Regression testing confirms that recent modifications to a software
program haven’t had an unfavorable impact on its current features.
This effective method makes use of automation technologies to
perform a large number of tests frequently, guaranteeing stability and
functionality following upgrades and offering a thorough analysis of
any errors.
There are numerous approaches that can be used, such as Selective
Strategies, Retest-All Strategies, Progressive Regression Testing, and
Corrective Regression Testing. Regression test methodologies
include, but are not limited to, conducting exploratory testing and
running high priority tests first.
Regression testing saves you time and effort, even if it uses a lot of
resources. It produces the most output while making the lives of
developers and testers easier throughout the agile software
development lifecycle.
Source: This article was originally published on TestGrid.