Non-Regression Testing: The Key to Faster and More Reliable Software Updates

Non-Regression Testing:
Ensuring Stability Without
Wasting Time
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A developer’s code changes may impact the software’s functionality.
Even minor changes can have unanticipated consequences or result in the appearance
of new bugs. For example, we use regression testing to detect newly discovered
problems.
Regression testing is the process of re-running tests to ensure that code changes do
not affect existing functionality.
There are times when there isn’t enough time or resources to run regression tests. A
testing team can only examine the system modules modified. They do not perform
complete regression testing. This is known as non-regression testing.
Non-regression testing is a technique for determining whether a new or modified
functionality works properly while assuming that the previous functionality was
unaffected.
For example, when using non-regression testing, testers examine only the evolving
unit or module rather than the entire product, saving resources and time. In such
cases, UI automation testing plays a crucial role by allowing teams to efficiently
validate UI changes without manually checking every functionality, ensuring that the
new interface does not disrupt the user experience.
What Is Non-Regression Testing?
Non-regression testing is a technique aimed to verify whether a new or modified
functionality operates correctly with the assumption that the previous functionality
wasn’t affected.
For example, when applying non-regression testing, testers check only the evolving
unit or module instead of the whole product, thus, saving resources and time.
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Steps of Non-Regression Testing
● Establish a benchmark software release.
● Define a set of routines capable of stimulating as many software functions as
possible.
● Run these routines on both software (the benchmark and the new release under
test) and collect data that reflects their behavior.
● Analyse this data using a post-processing tool to produce statistical results.
● Report the outcome.
● Exploratory testing follows similar steps to non-regression testing but differs in
its analysis phase and focus, resulting in different results and conclusions.
The non-regression testing goal is to see if any undesirable behavior emerges following
the most recent software modifications.
There, the new application behavior is previously known, allowing the identification of
an eventual regression (bug).
Exploratory testing, on the other hand, aims to discover how the software works,
balancing testing and learning and encouraging testers to create new test cases.
Regression and Non-Regression Testing
While regression testing aims to ensure that a software bug has been successfully
corrected by retesting the modified software, the goal of non-regression testing is to
ensure that no new software bugs have been introduced after the software has been
updated.
In general, this disparity in definitions can be assumed to be based on the results of
each test.
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When a new software version is released with no new features compared to the
previous version (i.e., the differences between the two versions are limited to bug fixes
or software optimization), both releases are expected to have the same functionalities.
In this case, the tests performed on both versions are not likely to produce different
results but rather ensure that existing bugs have been fixed and no new bugs have
been introduced. This testing methodology distinguishes regression testing.
On the other hand, if the new release includes new features or improvements that
cause the software to behave differently, the tests performed on the previous and new
versions may yield the following results.
Desired differences associated with expected new behavior, and undesired differences,
indicate a software regression caused by a side-effect bug.
Regression Testing Vs. Non-Regression
Testing
A regression test is typically a test that is we perform to ensure that the system’s
various functionalities are still working as expected and that the new functionalities
added did not break any of the existing ones. This could be a combination of
API/UI/Unit tests run regularly.
Non-regression tests can refer to various things depending on the context of your
projects, such as Smoke Testing or Unit Testing that are run during every code
check-in.
It could also refer to story-level testing carried out when a specific feature/requirement
in a story is being tested. Security testing, load testing, and stress testing may also be
performed during the development lifecycle.
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How Non-Regression Testing is different
from Nonparametric Regression Testing?
Nonparametric regression is a type of regression analysis in which the predictor does
not take a predetermined form but is built based on data information.
That is, no parametric form for the relationship between predictors and the dependent
variable is assumed.
Nonparametric regression necessitates larger sample sizes than parametric regression
because the data must supply both the model structure and the model estimates.
Non-Regression Testing Example
Non-regression testing can be incorporated into regression analysis. Here’s a rundown
of how it works.
For example, assume there is an existing functionality A tested and a new functionality
B that has just been added to the product.
So, for the time being, the program functionality is A+B. Non-regression testing will
only cover functionality B. However, new functionality – C – will be added later. If we
want regression testing, we’ll need to run the tests for A and B functionality.
Non-regression tests are incorporated into regression testing.
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Use of Non-Regression Testing
Non-regression testing is used when system components evolve, or new system
components (and functionality) are added.
Its goal is to ensure that the changes are correct and that no regression bugs have
appeared in the system due to the recent evolution.
In general, previous test sequences are launched to ensure that the system’s testing
quality has not deteriorated.
The test plan specifies the components to be tested following the evolution or
modification of a system component.
How To Automate Regression Testing?
Regression testing is a multi-layered process due to its extensive coverage and
technical complexity. Here’s a step-by-step guide to regression testing and
incorporating automation into the workflow.
At this stage, a developer estimates which system components will be changed and the
extent of the change.
Impact analysis of software changes:
● This stage entails outlining all of the possible consequences of the code change
across the system, identifying all systems affected by a new fix or feature,
estimating potential system damage and ways to deal with it.
● It is creating a strategy for regression testing. The testing team outlines the
workflow step by step at this stage. For example, a regression testing strategy
might look something like this: 1) collect test data; 2) estimate execution time
for test cases; 3) automate test cases; 4) execute tests; 5) report; and 6) iterate.
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● They are developing a test suite. At this point, a QA specialist creates automated
tests.
● Later, the regression when running automated tests on testing automation
engineer writes scripts for execution in a scripted language selected by the team
ahead of time.
● Running regression tests When running automated tests, prioritize cases and
evaluate test module reusability. Maintain a high frequency of testing and
establish a flexible reporting system.
● Reporting. At this point, QA specialists must explain the testing results to
stakeholders such as a project manager, the end client, and anyone who is
involved.
In addition, a developer must develop the metrics of analysis of the scope of testing
and elaborate on how the testing session helped the team achieve a goal set during
the planning stage to write a compelling summary report.
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Conclusion
Non-regression testing entails simply testing. Regression testing entails repeatedly
testing the application in two scenarios.
When a defect is discovered by a tester and corrected by a developer, the tester must
focus on the defect functionality and related old functionality.
Once the changes have been incorporated into the application, the tester must test
both the new and related old functionality to ensure that the related old functionality
remains the same.
A tester always carries out Non-Regression Testing. If any defects are discovered, then
you must perform Regression Testing.
Source: For more details, refer to TestGrid.
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