Non-regression testing: the complete guide to securing your updates

To secure your deployments and prevent each update from becoming a source of errors, it is crucial to integrate automated testing strategies. Non-regression testing (NRT) is an essential safeguard for ensuring the stability of your product.

What is a non-regression test (NRT)?

A regression occurs when a change to the code (bug fix, update, or new feature) unintentionally impacts previously stable parts of the application. The non-regression test (NRT), also known as regression testing, consists of verifying that these changes have not altered the behavior of existing features. In short, we ensure that what worked yesterday still works today.

What are the different types of non-regression tests?

Depending on your resources and objectives, several approaches can be adopted:

• TNR Corrective: Existing tests are reused without major modifications.
• Complete TNR: A comprehensive re-test of all product elements from the beginning.
• Selective TNR: Only those parts of the code that are potentially affected by the changes are targeted.
• Progressive TNR: New scenarios are created when product characteristics change.
• Partial TNR: Performed specifically during the merging of different code modules.
• Unitary TNR: Testing the code in isolation, component by component.

Why do non-regression tests?

The main challenge is ensuring software quality.

1. User Experience: A stable product strengthens your brand image and customer confidence.
2. Revenue protection: Preventing critical bugs (payment blocking, broken purchase funnel) avoids direct financial losses.
3. Cost-effectiveness: It is much less expensive to fix a bug during the testing phase than once the software is in production.
4. Security: TNRs can detectpotential vulnerabilities introduced by new lines of code.

When should you run your TNR campaigns?

We recommend integrating TNRs as early as possible in the product lifecycle. They are essential during:

• Correction of anomalies (bugs).
• The addition of a new feature.
• Modification of an existing feature.
• An update to the environment (data, servers).
• Source code optimization (refactoring).

What are the differences between functional validation and non-regression?

These two concepts are often confused, yet their objectives and processes differ.

On the one hand, the functional validation test aims to determine whether a new feature meets the initial requirements. It uses new scenarios, often executed manually at the outset to test positive and negative cases.

On the other hand, non-regression testing seeks to verify that existing systems have not undergone any code breaks. Here, we use test cases that are already known and stable. This is why NRT is the ideal candidate for automation, unlike validation testing, which often requires human intervention when it is first run.

Focus: What is a graphical non-regression test?

Also known as visual comparison test, it ensures that the user interface (UI) remains identical down to the pixel (pixel perfect) after an update. It checks the location, size, and color of elements (buttons, text, images) on different browsers and resolutions, while ensuring that the mandatory legal notices are present.

How do I run non-regression tests?

Regression testing is, by nature, time-consuming and repetitive. The use of an automated testing tool is therefore best practice. Automation enables continuous testing throughout the development cycle (CI/CD), identifying defects instantly before they reach your end users.

Note on limitations: Despite the power of automation, QA teams must prioritize the most critical scenarios to meet budget constraints and delivery deadlines.

Tired of regressions after every deployment? Discover how Mr SURICATE your TNRs without a single line of code to secure your continuous updates.