Regression testing is essential for identifying issues that may arise after updates or modifications to software, ensuring a seamless user experience and maintaining a company's reputation.

The complete guide on regression testing will teach you from basic regression testing to advance techniques. In this, we'll cover everything from what is regression testing to when it needs to be performed, how it must be implemented for proper effectivity. In the latter, we'll include some expert tips and best practices on optimizing the testing process toward a high quality in software product.

 

What Is Regression Testing?

Regression testing is the process of re-running portions of a mobile app or software to ensure that the new updates haven't introduced bugs, hence keeping the software reliable and stable.

In simple words, it is the process of re-testing the previously executed test cases to confirm that existing functionalities continue to work as expected.

This testing methodology encompasses several techniques such as functional testing, performance testing, security testing, and integration testing between different software components. It also involves the verification of data migration between systems.

 

Why Regression Testing?

Without regression testing, minor code changes can break the core functionalities, thereby introducing latent bugs that put the stability of the software at risk. Here are five important reasons why regression testing is necessary:

1. Maintainability

Incrementally, software is developed in agile development. This regression testing checks whether the changes do not cause harm to previously developed features while maintaining the general quality of the system.

2. Defect Reduction

Usually, bug fixing creates side effects in the code. Regression testing detects these bugs early, particularly in unstable parts of the software.

3. Better Communication

Regression testing provides a bridge between developers and testers. It guarantees that even slight modifications have been tested rigorously, nothing left behind.

4. Robustness and Stability

By rigorously testing dependent components and minimizing unnecessary dependencies, regression testing enhances the robustness and stability of the system.

5. Cost and Time Efficiency

Skipping regression testing may save time initially but can result in costly post-release fixes. Catching bugs early in the regression phase prevents expensive errors and protects user trust.

 

Regression Testing Example

Consider a bank’s financial software system that handles transactions, account management, and customer data. After a major update introducing new security protocols and loan management features, regression testing ensures the updates don’t negatively affect existing functionalities.

Pre-Update Scenario:

  • Transactions Module: Handles deposits, withdrawals, and transfers.
  • Account Management Module: Manages customer accounts.
  • Customer Data Module: Manages clients’ personal and financial information.

Update Details:

  • Implementation of new security protocols for transaction data.
  • Addition of a loan management feature to the account management module.

 

Regression Testing Steps

Re-Test All Transaction Types: Verify that deposits, withdrawals, and transfers work correctly without errors, and confirm that security measures don’t impact processing speed or accuracy.

Account Creation and Closure: Ensure account creation and closure processes operate as intended, with no data loss or corruption.

Loan Management Functionality: Test the integration of loan management features with existing functionalities to ensure seamless performance.

Security Checks: Validate that the new security enhancements are effective and do not block legitimate operations.

Data Integrity in Customer Data Module: Confirm that changes, such as adding a loan, update the customer’s financial profile accurately without errors.

End-to-End Testing: Simulate real-life scenarios, such as opening an account, depositing funds, applying for a loan, and transferring money, to ensure smooth operation across multiple modules.

 

Regression Testing Types

Regression testing can be performed in various ways, depending on the scope and objectives:

Unit Regression Testing: Focuses on testing individual units or components of code to ensure recent changes haven’t introduced bugs.

Partial Regression Testing: Targets a specific portion of the system after minor updates, ensuring that new changes do not adversely affect the unchanged parts of the system.

Complete Regression Testing: Involves testing the entire system after significant updates. This thorough approach ensures all functionalities work as intended.

Selective Regression Testing: A hybrid method where only a subset of tests, selected based on relevance to the updates, is run. It ensures that areas impacted by the changes are thoroughly tested without testing the entire system.

 

The Do’s and Don’ts of Regression Tests

Performing effective regression testing requires a balance between thoroughness and efficiency. Below are the key do’s and don’ts to streamline your testing process:

Do: Start Early

  • Implement testing strategies at the beginning of the project to identify bugs early.
  • Continuous Integration (CI): Integrate automated regression tests into your CI pipeline to receive immediate feedback with each code commit.
  • Test-Driven Development (TDD): Write tests before coding to validate each new piece of code as it's written.

 

Don’t: Undervalue CI

  • Continuous integration ensures flexibility and quick feedback in agile development.
  • Regression testing is vital for the success of CI pipelines, enabling continuous improvement and ensuring quality throughout each sprint.

 

Do: Automate When Possible

  • Automate repetitive tests that don’t change frequently to save time and ensure consistency. Automated tests reduce human error and run efficiently across multiple cycles.

 

Don’t: Rely Too Much on Automation

  • Some tests, such as those involving user interface changes, require manual intervention to evaluate design elements and handle complex, dynamic scenarios effectively.

 

Do: Prioritize Test Cases

  • Focus on critical features that are most prone to change or have a significant impact on the system. For example, prioritize transaction-related tests in a banking app when updating security features.

 

Don’t: Ignore Non-Critical Areas

  • Even small changes can introduce bugs in overlooked areas, such as a minor SQL query affecting data display. These bugs can impact user experience and functionality.

 

Do: Maintain a Comprehensive Test Suite

  • Regularly update test cases to align with code changes. A well-maintained test suite ensures comprehensive coverage and accurate results.

 

Don’t: Neglect Test Maintenance

  • Obsolete test cases can waste time and generate false positives or negatives. Review and update your test suite regularly to maintain its relevance and efficiency.

 

Do: Use Parallel Testing

  • Run tests simultaneously across different environments to optimize resources and speed up the testing and development process.

 

Don’t: Skip Testing After Minor Changes

  • Small updates can have unforeseen consequences. Always include regression tests in your strategy, regardless of the change’s perceived size.

 

Regression Testing Challenges

Regression testing can be complex and demanding, depending on the software's architecture and the nature of code changes. It requires meticulous planning and strategic solutions to ensure impact-focused testing. QA teams perform detailed risk assessments before executing the regression test suite to identify all affected areas in the system.

Here are some common challenges:

Time and Resource Intensive: Comprehensive testing for every update is time-consuming and increases the workload. This often requires additional testers or automation tools. Repetitive testing can also lead to fatigue, resulting in overlooked issues.

Automation Challenges: While automation speeds up testing, it requires technical expertise and regular maintenance. Over-reliance on automation may miss edge cases or produce false positives, compromising testing accuracy.

Complexity Management: As features evolve, the growing number of test cases becomes difficult to manage, especially when integrating new functionality. Risk-based testing helps QA teams focus on critical areas to manage complexity effectively.

Frequent Updates to Test Cases: Regression tests must align with frequent code updates. Outdated test cases can create coverage gaps and complicate test documentation maintenance.

Dependency Between Features: Changes in one feature can cause a ripple effect across others. QA teams conduct risk assessments to identify dependencies and execute relevant test cases.

 

How to Do Regression Testing

Regression testing is typically done by re-executing previously run test cases on modified software to ensure its functionality remains intact. Here’s the step-by-step process:

Step 1: Identify Source Code Changes and Measure Their Impact

  • Determine the scope and nature of application modifications, such as new features, bug fixes, or environmental changes.
  • Identify affected areas to direct testing efforts effectively.

Step 2: Select and Prioritize Test Cases

  • Choose test cases for the regression suite based on their relevance to the updates:
    • Does the function impact critical features?
    • Is the feature newly introduced or frequently updated?
    • Does the code have a history of defects?
  • Prioritize tests for essential and vulnerable functionalities.

Step 3: Create a Regression Testing Strategy

  • Develop a strategy outlining goals, scope, timing, resources, and techniques. Estimate the required time and allocate resources accordingly.

Step 4: Set Your Test Frequency

  • Define how often regression tests will run. For larger systems, use automation to manage frequent tests efficiently.

Step 5: Use Test Automation

  • Automate regression testing to run large test suites quickly and accurately. Reuse automation scripts for future tests, saving time and effort.

Step 6: Run Manual and Automated Regression Tests

  • Start with automated tests for efficiency. Use manual testing for complex scenarios or areas not covered by automation.

Step 7: Review Test Results and Resolve Issues

  • Analyze test outcomes to identify failures. Investigate and resolve issues, then re-run tests to confirm fixes. Repeat this process until desired quality is achieved.

Step 8: Revise and Improve the Test Suite

  • Regularly update the test suite to reflect application changes. Add new test cases, modify existing ones, and remove obsolete tests to maintain relevance.

 

How to Do Manual Regression Testing

Manual regression testing involves human testers executing test cases after updates, focusing on subtle issues that automation may miss. While time-consuming, it’s especially useful for complex systems.

Steps for manual regression testing:

  • Define the regression testing strategy for the round.
  • List the updates made to the product.
  • Identify areas likely impacted by the updates.
  • Include known problem areas or additional components in testing.
  • Distribute the testing workload across the team.
  • Create detailed bug reports with steps, screenshots, and videos.
  • Confirm testing coverage with available resources.
  • Save and reuse test cases for future testing.

 

How to Do Automated Regression Testing

Automated regression testing reruns test cases efficiently after updates, leveraging the power of tools and scripts.

Steps for automated regression testing:

  • Identify application parts requiring regression testing based on code changes.
  • Select an automation tool that suits your application and integrates with other systems.
  • Create automation scripts, breaking test cases into manageable scenarios.
  • Build a comprehensive regression test suite covering all critical areas.
  • Integrate automated tests into your CI/CD pipeline to streamline execution and monitor results.

 

Automated Regression Testing Tools

Automated regression testing tools play a vital role in streamlining the testing process and improving accuracy. Below are some popular tools widely used in the industry:

Selenium

Selenium enables testers to simulate user interactions and execute test scripts across multiple browsers and platforms. It provides robust reporting capabilities, making it ideal for web application testing.

Ranorex

Ranorex simplifies regression testing with its user-friendly interface and advanced features. It supports test recording, replaying, and automation across diverse platforms and technologies, making the process efficient and comprehensive.

WATIR

Watir (Web Application Testing in Ruby) is an open-source tool that’s easy to use, especially for beginners. It allows testers to create, manage, and run test cases with simplicity and cost-effectiveness.

Appium

Appium is an automation tool compatible with multiple platforms and supports various programming languages, including Ruby, Python, Java, JavaScript, and C#. Its WebDriver-based interface ensures simplicity and stability during upgrades.

 

How to Improve Your Regression Testing Process

To address challenges and ensure effective regression testing, consider implementing these best practices:

Establish a Regression Testing Strategy: Define testing frequency and identify critical test cases. Regularly update the strategy based on software risk assessments.

Use Different Testing Methods: Incorporate unit, manual, and functional tests into the regression suite for comprehensive coverage.

Conduct Regular Regression Tests: Execute regression tests consistently after each update or release to detect and resolve issues early.

Prioritize Test Cases: Focus on testing critical business functions to maximize efficiency and minimize risk.

Implement Automated Regression Tests: Use automation to save time, expand test coverage, and improve accuracy.

Maintain an Up-to-date Regression Test Suite: Regularly update test cases to align with code changes, preventing coverage gaps.

Collaborate with Developers: Ensure synchronization between regression testing and ongoing development for seamless integration of changes.

Document the Process: Record test frequencies, test cases, and defects for consistency and reproducibility.

Continuously Improve: Analyze results to refine testing procedures and maintain effectiveness.

 

How to Design a Regression Testing Strategy

A robust regression testing strategy includes four key components:

Testing Objectives

Define potential risks and the acceptable level of risk. Determine how failures might affect users and the organization.

Scope

Identify functional and non-functional testing aspects. Specify included and excluded test types or methodologies.

Entry and Exit Criteria

Set conditions for starting and concluding tests, such as a required number of successful sprints or completion of testing goals.

Test Suite Design

Design a test suite for maximum coverage with minimal cases. Include strategies for addressing critical bugs and specify environments for testing.

 

Regression Test Cases

For example, when Amazon introduces a new product category like "Smart Home Devices," regression tests ensure functionality, reliability, and performance remain intact. Key tests might include:

Homepage Functionality: Verify the new category is listed correctly without disrupting other categories.

Category Navigation: Ensure smooth navigation to and from the new category.

Search Functionality: Test accurate filtering and display of search results specific to the new category.

User Accounts: Confirm proper account operations, including purchases in the new category.

Payment Processing: Assess secure, error-free transactions for the new category.

Mobile Responsiveness: Validate responsive design for various devices accessing the new category.

Failures in these tests should be documented and addressed promptly to maintain user experience. Automation can significantly streamline such large-scale regression testing processes.

 

In-House vs. Outsourced Regression Testing

In-House Testing

Pros: Complete control over the process, seamless integration into the development lifecycle.

Cons: Requires internal expertise, time, and budget.

Outsourced Testing

Pros: Cost-effective, access to expert teams and advanced tools.

Cons: Success depends on selecting the right partner.

The choice between in-house and outsourced regression testing depends on factors like budget, timeline, and available resources.

 

Final Thoughts

By leveraging the right regression testing tools and methods, you can identify and eliminate defects early in the development process. Establishing a solid strategy, maintaining an updated test suite, and collaborating effectively with your team ensure the delivery of high-quality, reliable software.

Rohit Gupta
Rohit Gupta
COO
Rohit harnesses his extensive knowledge of advanced technologies such as Blockchain, AI, and RPA to create solutions for diverse industries, including healthcare and customer experience management. Rohit's expertise in digital transformation enables businesses to achieve their strategic objectives.