Regression Testing: Your Complete Guide for 2025

As businesses continue to leverage Microsoft Dynamics 365 for seamless operations, ensuring that new updates and customizations don't disrupt existing processes is critical. With every release and One Version updates, regression testing becomes essential to verify that updates, patches, or new features haven’t caused unforeseen issues.

In 2025, regression testing in D365 is increasingly driven by automation and integration with CI/CD pipelines, helping businesses reduce downtime, improve testing speed, and minimize risk. These advancements ensure that organizations using D365 can quickly adapt to new functionalities while maintaining system stability and performance.

In this guide, we’ll dive into the latest strategies, benefits, and types of regression testing in D365, helping you stay competitive by streamlining testing processes and ensuring your system remains robust, even as it evolves. But let's start with the base.

What is regression testing

Regression testing is the process of testing software to ensure that recent changes — such as updates, fixes, or new features — haven't negatively affected existing functionality. Simply put, regression testing examines the system to determine if there are any “regressions” after modifications have been made. Hence, in a way it is retesting, although these are slightly different concepts.

Note: What is the difference between regression testing and retesting? Regression testing checks whether new changes have unintentionally affected existing functionality, ensuring the system as a whole remains stable after updates or fixes. Retesting, however, focuses specifically on verifying that previously identified bugs have been successfully fixed without reintroducing the same issues.

When to perform regression and retesting

Delving into the details... When software undergoes changes, such as bug fixes, system updates, or new feature additions, it’s crucial to verify that these changes haven’t broken previously working components. Regression testing ensures that the application continues to function as expected without introducing new issues. This type of testing often involves rerunning previously successful test cases on the updated version of the software to confirm that it still meets the required standards.

For example:

Bug fixes: Suppose a developer fixes an issue with a login feature. Regression testing would be used to confirm that the fix hasn't caused problems in other areas, such as account creation or password reset functions.

New features: Adding a new reporting feature to an existing CRM system requires regression testing to ensure that the new feature does not interfere with existing functionalities like customer data management or sales tracking.

System updates and upgrades: If a system is upgraded with a newer version of its database or server software, regression testing helps ensure that no critical operations — such as data retrieval or user access — are broken in the process.

When to perform regression testing in D365

Regression testing is critical for maintaining the stability and performance of Microsoft Dynamics 365, especially in environments with frequent updates, customizations, and integrations. Here are the key scenarios where regression testing is essential:

After D365 updates and patches

Microsoft frequently releases updates, such as security patches, feature enhancements, and monthly service updates. Each update has the potential to disrupt existing configurations, workflows, or integrations. Regression testing ensures that these updates do not adversely affect your system’s established functionality, such as customer records, reporting, or automated workflows.

Following bug fixes

After introducing new features

Adding new features or implementing customizations in D365 can unintentionally alter the behavior of existing modules. Regression testing validates that these new changes integrate seamlessly without disrupting current operations such as sales automation, customer service workflows, or financial reporting.

Post-code refactoring or optimization

When developers optimize or refactor the codebase in D365 to improve performance or maintainability, regression testing is necessary to confirm that the changes haven’t negatively impacted existing processes or configurations, such as integrations with Power Platform or external services.

During system integrations

D365 often integrates with other systems, such as ERP solutions, third-party apps, or custom APIs. Regression testing ensures these integrations function as intended and do not interfere with core modules like CRM, supply chain management, or finance and operations.

How to perform regression testing

Regression testing is best done at key stages of the software update cycle:

Before updates

Conduct regression testing in D365 to ensure the current system is stable and bug-free before implementing any updates. This sets a baseline for the changes to come.
During updates

Perform in-process regression testing while updates are being applied to verify that new features or fixes integrate properly without causing issues in the existing system.
After updates

Post-update regression testing ensures that the applied updates haven’t introduced new issues and that the core functionality of the system, such as finance or operations, continues to work smoothly.
Continuous testing

In agile environments like D365, continuous regression testing throughout the development process helps maintain stability and reduce risks during frequent updates and customizations.

For example, One Version service updates are applied regularly, and regression testing is essential throughout the entire update process. Before the update, regression testing ensures that no major issues exist in the current system. During the update, in-process regression tests confirm that new features, bug fixes, or patches integrate smoothly. Finally, after the update is deployed, post-upgrade regression testing verifies that existing features such as financial management or inventory tracking are not affected by the update.

Why regression testing matters in 2025

In 2025, the right regression testing tool is more crucial than ever as software becomes increasingly complex and the demand for frequent updates and new features intensifies.

Firstly, with the rapid pace of agile development and continuous delivery, software systems are frequently updated with new features, bug fixes, and security patches. Regression testing ensures that these changes do not inadvertently break existing functionality, preserving the stability and reliability of the system. As businesses increasingly rely on complex, interconnected systems, the risk of causing unintended issues with new code grows, making regression testing a vital safeguard.

Secondly, the rise of AI and automation tools is enhancing regression testing efficiency, enabling businesses to test more frequently and at a faster pace without compromising quality. These advancements allow for more comprehensive testing, ensuring that applications meet the high standards of performance and user experience expected in today’s fast-moving market.

Types of regression testing

H2_ Types of regression testing

Unit regression testing

Unit regression testing focuses on testing individual units or modules within the system after code changes. It’s used to validate that the functionality of the specific part of the system works properly after the code has been modified.

Example: Testing a single function or module after modifying its logic or adding new code.
Partial regression testing

Partial regression testing involves testing a smaller portion of the application, but with a bit more focus than selective regression testing. It tests the integration of new changes with the existing codebase to confirm that modifications don’t introduce errors.

Example: After adding a feature to a mobile app, partial testing would check the impact of that feature on other related components, like the user interface or database.
Retest-all regression testing

As the name suggests, retest-all regression testing involves testing the entire application or system after any update or modification. This is done to ensure that all areas of the software are working as intended after a significant update, especially if the system is large or interconnected. This type of regression testing is comprehensive but can be resource-intensive.

Example: After a major software update, testing all features (including newly added and existing ones) to confirm everything works.
Selective regression testing

This type focuses only on the parts of the application that have been affected by changes. It’s used when changes are localized or when the update or feature does not impact the entire system. Selective regression testing is less time-consuming compared to retest-all testing.

Example: Testing only the modules directly affected by code changes, such as a backend update or database structure change.
Complete regression testing

Complete regression testing involves testing all the features and components of the software from scratch after major updates or significant changes. This ensures the software works as expected after new features are integrated. It’s a thorough approach often taken in large-scale projects or when the system has undergone major refactoring.

Example: After refactoring a software platform to adopt new technologies or frameworks, complete regression testing ensures no part of the system is broken.

If you want to explore these types of regression testing in detail, follow this link.

Manual vs. Automated regression testing: key differences

When it comes to regression testing, the choice between manual vs. automated testing can make or break your software quality efforts. Manual testing shines for its human insight in complex scenarios, but for speed, consistency, and handling repetitive tasks, automation takes the lead.

Understanding the key differences isn’t just about choosing a method — it’s about unlocking faster updates, better performance, and smarter resource use in today’s fast-paced software world.

What are the key differences between manual and automated testing?

1. Speed and efficiency

Manual testing
Time-consuming and slower, as testers execute tests step-by-step, especially with large applications or frequent updates. Each test case needs to be manually executed and verified, making the process longer and more prone to human error.
Automated testing
Automation significantly accelerates testing cycles. Automated scripts can quickly run through large test suites, providing immediate feedback. A key advantage is the ability to use scheduling tools for parallel execution, which allows tests to be run concurrently rather than sequentially. This drastically reduces the time required for testing. Additionally, automated tests can run outside of working hours, freeing up manual testers to focus on more complex tasks.

Case example
In a real-world scenario, automating test runs and scheduling them to occur in parallel can reduce the overall time required for testing. While manual testing might take hours or even days, automated tests can execute multiple test cases at once, and can be scheduled to run after hours, improving team productivity. This means faster releases and minimal disruption to day-to-day operations.

For instance, here's how automation speeds up regression testing in the finance unit:

Name of the tested process	time [s]
Report Tax	48
Manual General Ledger Postings	97
Purchase order/invoice - No deviation	406
Creating/Adjustments/Depreciation and Scrapping of Fixed Asset equipment	591
Purchase order/invoice - Price deviation, including item price	333
Disposal - Sale of Fixed Asset, equipment free text invoice	329
Purchase order/invoice - Quantity deviation	335
Approve invoices - ExFlow web	195
Send payment to bankfile in EUR	416
Freetext invoice and manual customer payment	283
Foreign currency revaluation - AP	104
Approve invoices - ExFlow web (change precoding, split invoice and forward)	217
Approve invoices - ExFlow web (coding on web)	214
Send payment to bankfile in SEK/Bankgiro	444
Currency revaluation AR	648
Send payment to bankfile in USD to country not in US	418
Total	5078

Time needed to execute all Test Cases in sequence manually	1.4h
Scheduler execution time optimization in sequence/parallel	45min
Saved 53% time thanks automation and schedule optimization	55min

2. Consistency and accuracy

Manual testing: Susceptible to human error, potentially leading to inconsistent results.

Automated testing: Highly consistent, with scripts running tests in the exact same way every time, ensuring reliable results.

3. Cost

Manual testing: Higher long-term costs due to continuous human involvement, especially with frequent updates.

Automated testing: Initial setup costs are higher, but it becomes cost-effective over time due to reusability and faster execution.

4. Scalability

Manual testing: Difficult to scale for large or complex systems, especially with frequent updates.

Automated testing: Scales well, allowing for running tests across multiple environments and handling more complex applications.

5. Maintenance

Manual testing: Requires ongoing updates and adjustments for every change, which can be time-intensive.

Automated testing: While requiring occasional updates, it is generally easier and quicker to maintain compared to rewriting manual test cases.

6. Best use cases

Manual testing: Best for smaller systems, one-time tests, or scenarios where human intuition and judgment are necessary.

Automated testing: Ideal for large-scale systems, frequent updates, and environments with continuous integration/deployment (CI/CD).

Summary: manual vs automated regression testing

Automated regression testing is particularly beneficial in the D365 FSCM environment, where frequent system updates — such as those from Microsoft's One Version updates — require continuous testing across integrated processes. Automation allows for fast, consistent, and repeatable tests, ensuring that core functionalities like financial transactions, inventory management, and order processing continue to operate smoothly after each update.

However, there are scenarios in D365 FSCM that require a more nuanced approach. Complex customizations, integrations with third-party systems, or user experience (UX) testing often benefit from manual regression testing. For example, validating that custom workflows in procurement or finance still work as expected after an update might require the expertise of a tester familiar with the specific setup.

The optimal approach for D365 FSCM users is to automate 90% of regression tests—particularly for standard, high-volume tasks such as general ledger entries, procurement processes, and sales order management. Leave 10% for manual testing to handle complex cases like customizations, UI interactions, or areas where human judgment is required to evaluate business logic or performance.

Benefits of automated regression testing

Automated regression testing brings significant advantages to software development, particularly when dealing with frequent updates, complex systems, or large-scale applications. By automating the process, businesses can ensure that regression testing is done efficiently, thoroughly, and consistently, without the time and effort required for manual testing.

Here are the key regression testing benefits:

Speed

Automated tests can be executed much faster than manual tests, significantly speeding up the testing process. This is especially important in agile environments where frequent releases are the norm.

For example, automated tests can be run in parallel across different environments or platforms. This reduces testing time significantly, especially when the software needs to be tested on multiple devices or operating systems.
Consistency and reliability

Unlike manual testing, automated tests can be executed consistently without human error. This ensures that the same tests are run every time, with the same results, providing greater reliability and helping to maintain software quality across multiple releases.
Cost savings in the long run

While setting up automated regression tests may require an initial investment in time and resources, it quickly pays off. After the tests are automated, they can be reused for future updates, saving on the costs associated with manual testing. The time saved on testing also allows development teams to focus on innovation and other critical tasks.
Scalability for complex systems

Automated regression tests are ideal for large-scale systems or applications that undergo frequent updates. They can cover a broad range of functionalities and integrate with continuous integration/continuous delivery (CI/CD) pipelines, allowing businesses to scale testing efforts easily as the software grows.
Better test coverage

Automated testing can run more tests in less time compared to manual testing, allowing for broader test coverage. This includes more test cases and deeper functional testing across different system components, ensuring that nothing is overlooked and all parts of the software are properly tested.
Supports CI/CD

Automated regression testing fits seamlessly into CI/CD workflows, allowing for frequent, incremental code changes to be tested automatically. This aligns perfectly with modern development methodologies where software is continuously delivered and updated, ensuring quality is maintained throughout.
Improved ROI

Although there is an initial cost to set up automated tests, the return on investment increases as these tests can be reused across various projects and software versions. Automation reduces the reliance on manual labor and speeds up the testing process, which ultimately improves software delivery time and quality.

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Challenges in regression testing and how to overcome them

Regression testing is essential to maintain software quality, but it comes with its own set of challenges. In fact, organizations often struggle with testing during frequent software releases, making it crucial to address the obstacles that hinder efficient testing.

Here are the top three challenges in regression testing and how to overcome them:

Challenge 1. Maintaining test case relevance

As software evolves, test cases can quickly become outdated or irrelevant, especially when features are modified, or new ones are added. Keeping regression tests aligned with the current version of the software can be time-consuming and error-prone.

How to solve: Automate your test cases and use continuous integration (CI) tools to ensure they are executed every time the code is updated. Additionally, adopt version control systems for test cases to ensure that test scripts are always aligned with the latest features. Regularly review and update test cases to remove redundant ones, adding new tests as needed.

Challenge 2. Test execution time and efficiency

Regression testing can become lengthy, especially with large applications or when testing across multiple environments and platforms. As software complexity increases, so does the time required to run these tests manually.

How to solve: To overcome this, implement automated regression testing. Use tools that support parallel test execution and scheduling to run tests outside working hours. This reduces testing time significantly and allows for more frequent and thorough testing without adding extra workload to the team.

Challenge 3. Flaky tests and unstable test environments

Flaky tests, which produce inconsistent results, and unstable testing environments, can lead to false positives or negatives. This makes it difficult to trust the test results, causing delays and unnecessary troubleshooting.

How to solve: Ensure stable and reliable test environments. Additionally, implement “retry logic” in automated tests to handle intermittent failures. It's also crucial to regularly monitor and maintain the test environments to ensure they remain stable.

best practices

How to choose the right automated regression testing tool

Selecting the right regression testing tool isn’t just a technical choice — it’s a game-changer for efficiency and system quality. For intricate platforms like D365, where updates are frequent and complexity runs deep, automated testing tools ensure you stay agile without risking stability.

Key factors to consider:

Automation needs: Choose a tool that easily integrates with your CI/CD pipeline and supports parallel test execution. This ensures faster testing cycles, especially for large, complex systems like D365.

Cost-effectiveness: While automated tools may require a higher initial investment, they save significant time and money over the long term by reducing manual testing efforts, accelerating release cycles, and catching issues earlier in the development process.

Scalability and flexibility: As your project grows, it’s crucial to select a tool that can scale with it. Look for tools that support different platforms, environments, and versions, ensuring consistent and reliable testing as your system evolves.

Ease of integration: The tool should seamlessly integrate with existing tools like Azure DevOps, JIRA, or other project management platforms. Look for one that provides robust reporting and analytics to help track testing progress and quickly identify any issues.

The right regression testing tool should meet your team’s specific requirements and accommodate the complexity of your system. For D365 and other large-scale platforms, having a solution that offers efficiency, scalability, and seamless integration with your existing workflows can transform your testing process. Executive Automats solutions are tailored to your needs, allowing you to confidently automate regression testing and maintain system quality through rapid updates and continuous improvement.

Contact us and get your free trial to learn more about how Executive Automats for Testing can help transform your testing strategy and ensure the success of your D365 projects.