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Sanity Testing vs Regression Testing: Differentiating the Software Testing Techniques

When testing software, various techniques are utilized to ensure that the application functions as expected. Two of the most common methods employed are sanity testing and regression testing. Both play important roles in the testing process, albeit with distinct purposes.

We’ll compare sanity testing vs regression testing in this post, including when to use them, their benefits, and how they differ. You’ll learn their purposes, how to perform them, and when to apply them during the software development life cycle.

With a solid understanding of these two fundamental techniques, you can choose the right testing approach for your needs. We’ll also compare sanity and regression testing side-by-side on key factors, so you can determine which is best suited depending on your use case.

What is the Difference Between Sanity Testing and Regression Testing?

Bottomline Upfront: Sanity testing performs cursory checks on core functionality after changes, while regression testing thoroughly re-executes test cases to confirm bugs were not introduced.

Sanity testing aims to establish stability for further testing, whereas regression testing seeks to comprehensively validate new features and fixes against a broad set of test cases to prevent defects. These differences are detailed as you read on.

What is Sanity Testing in Software Testing?

Sanity testing is a type of software testing performed after receiving a new build, a code change, or after fixing a bug to verify that the proposed functionality works as expected by conducting cursory tests.

Sanity testing determines if the application is testable in its current state or if it would be a waste of time and resources to proceed with thorough testing.

Test cases are not usually created, but you may utilize a basic script to evaluate the software which allows you to identify issues early before conducting extensive testing.

Sanity testing focuses on core functionality rather than thoroughly testing the entire application. You can perform sanity checks manually or use test automation to speed up the process.

What is the Primary Purpose of Sanity Testing in Software Testing?

The primary purpose of sanity testing is to verify that any new code changes or bug fixes did not break the core functionality of the application.

By performing sanity checks, you can quickly validate that the basic workflow is intact before proceeding with more rigorous testing techniques. This allows you to save time and resources that would be wasted testing an unstable build.

How to Do Sanity Testing for Software

You can perform effective sanity testing for software by following these key steps:

1. Identify Scope of Testing

First, you need to identify which modules or functionalities require sanity testing. Focus on areas that were recently changed or added. There is no need to sanity test parts of the code that were untouched.

2. Create Rough Test Cases

While formal test cases are not needed, you should create a basic script to assess the impacted areas. Outline the key workflows to evaluate whether the core functions still work as intended.

3. Execute Tests

With your scope defined and scripts created, execute the sanity tests. You likely want to conduct testing manually at this stage for speed. Alternatively, utilize test automation tools to accelerate execution.

4. Evaluate Results

Analyze the results from sanity testing. If major issues are discovered that prevent basic usage, the build fails and should be rejected. Minor bugs can be fixed later.

5. Report Findings

Document your test findings and share them with the development team. Critical defects blocking testing should be reported immediately while non-urgent bugs can be logged for future repair.

When to Use Sanity Testing in Software Testing

Knowing exactly when to utilize sanity testing is key to maximizing its value. The right timing includes:

Before Regression Testing Cycles

Conduct sanity tests before full regression test cycles to validate that the build is stable enough for exhaustive testing. This prevents wasting time and effort on a faulty build.

After Code Changes

Any code modifications should be followed with a sanity check to quickly confirm no unintended side effects. This provides rapid feedback to developers on the code quality.

After Bug Fixes

Once defects are fixed, sanity testing verifies the resolutions did not impact other areas of the software. It builds confidence before further testing.

During Sprint Testing

Agile teams can perform sanity checks before deploying each Sprint to catch severe issues early. This reduces downstream defects and rework.

Before Releases

Right before a production release, a sanity test provides one final confirmation of functionality and stability.

Advantages of Sanity Testing in Software Testing

Sanity testing provides several key benefits:

Saves Time and Resources

By performing a sanity check, you avoid wasting significant effort testing an unstable build. Failing quickly preserves time and resources for future test cycles.

Provides Early Feedback

Sanity testing gives rapid feedback on the current quality and stability of the application after changes. This way you can address critical defects before they propagate downstream.

Reduces Risks

Catching issues early with sanity testing reduces the risks of major functionality being broken. It provides confidence in the build before conducting exhaustive testing.

Requires Minimal Effort

Sanity tests are quick and lightweight. They give you rapid validation without extensive test case preparation or execution effort.

Determines Testability

The sanity check validates whether the application is ready for formal testing or if more work is needed first thereby preventing wasted time assessing an untestable build.

What is Regression Testing in Software Testing?

Regression testing is a software testing practice that validates application behavior and functionality remains intact after changes. It ensures that bug fixes, feature enhancements, or any other modifications do not impact areas of the software that previously worked as expected.

You execute regression tests after sanity testing changes to verify thorough coverage beyond the basic workflows.

Regression testing re-runs existing test cases and scripts against the updated application to check for defects, inconsistencies, or unwanted side effects from the changes. It provides assurance that the full set of features still functions properly.

Regression testing can be performed manually but is often automated for efficiency, especially since it involves repeatedly executing the same checklists of test cases. This methodical testing technique protects against unintended breaks and defects creeping in as software evolves.

Types of Regression Testing

Several types of regression testing can be utilized and selecting the right regression approach depends on the application changes and resources available.

Here are some types of regression testing:

Full Regression Testing

This exhaustively executes all test cases and scripts to provide comprehensive coverage. It should be done during major releases or system-wide updates.

Partial Regression Testing

Only a subset of test cases focused on the modified areas are executed. This provides targeted coverage when changes are isolated.

Functional Regression Testing

The regression suite focuses on validating business functions and workflows. This ensures user scenarios work as expected after changes.

User Interface Regression Testing

The UI and design elements are specifically regression-tested to check for defects, layout issues, or inconsistencies after updates.

Performance Regression Testing

Performance test cases are executed to verify response times, load capacity, and system resource utilization were not impacted negatively.

What is the Primary Purpose of Regression Testing in Software Testing?

The core objective of regression testing is to verify that bug fixes, new features, configuration changes, or any other application modifications did not break existing functionality.

Regression testing aims to prevent the introduction of new defects or issues in the code and ensures that the software still behaves as intended after changes are made.

How to Do Regression Testing in Software Testing

Conducting effective regression testing requires some key steps:

1. Identify Scope

Determine which sections of the application were modified and require regression testing. Changes often impact dependent functionality or components as well.

2. Select Test Cases

Choose relevant test cases that cover the updated modules, flows, and use cases. Mix automated and manual scripts as needed.

3. Configure Test Environment

Ensure the test environment is configured properly and test data is ready to support execution.

4. Execute Tests

Run the regression test suite per your test plan. Automate execution where possible for efficiency.

5. Analyze Results

Evaluate results to identify newly introduced issues, inconsistencies, or other undesirable side effects from the changes.

6. Report Defects

Log defects in your tracking system and assign them to appropriate teams for repair. Defects should be prioritized accordingly.

7. Retest and Re-execute

Fixes must be retested via the regression suite. Rerun tests until all critical defects are closed and acceptable quality is achieved.

8. Update Tests

Finally, update the regression suite with any needed modifications to the test cases or data sets. Expand coverage as required.

Related: Difference Between Smoke Testing and Sanity Testing

When to Use Regression Testing in Software Testing

Knowing when to apply regression testing is critical for maintaining quality. Here are ideal times to use regression testing:

After Code Changes

Any code modifications should trigger regression testing to detect unintended side effects and confirm that the existing functionality was not impacted.

After Bug Fixes

Once defects are repaired, re-executing test cases verifies the fixes and that no new issues were introduced.

During Integration Testing

When integrating updated modules and components, use regression tests to uncover integration bugs early.

Before Major Releases

Conduct full regression suites to validate overall system quality and stability before broad deployments.

During Maintenance Releases

Regular maintenance releases should include regression testing to prevent regressions and quality erosion over time.

After Infrastructure Changes

Updates to environments, hardware, OS, databases, etc require regression testing to check for compatibility issues.

Advantages of Regression Testing in Software Testing

Using regression testing for software testing has a ton of benefits including:

Detects Bugs Early

By executing tests after changes, defects can be identified right away before impacting end users which allows faster remediation.

Reduces Risk

Regression testing lowers the chances of software quality degradation over time and provides ongoing confirmation that the system works as intended.

Saves Time and Money

Detecting bugs early through regression testing is far less expensive than fixing issues after deployment. It also prevents costly rework.

Improves Quality

Continuous regression testing results in more stable software with each iteration as it enables incremental quality improvements.

Provides Confidence

Passing regression test cases verifies existing functionality was not affected by modifications. This confidence enables faster releases.

Automatable

Automated regression testing enables fast re-testing with minimal effort as tests can be scheduled and run unattended.

Sanity testing vs Regression testing: Feature Comparison

While sanity testing and regression testing are complementary testing techniques, they have different objectives as highlighted in this head-to-head comparison:

Testing Objective

Sanity testing provides an initial assessment of stability and aims to quickly validate whether critical functionality still works after changes.

In contrast, regression testing seeks to thoroughly verify all functionality has not regressed by ensuring no defects were introduced and there are no unintended side effects from changes.

Scope

Sanity testing narrowly targets a small set of critical test cases related to the modified areas of highest risk.

Regression testing comprehensively covers an extensive set of test cases, including both automated scripts and manual steps. It tests all connected functionality that could be potentially impacted.

Depth

Sanity testing performs only cursory tests using the happy path scenarios to check for basic conformance.

Regression testing executes test cases using various data sets and scenarios. Rigorous boundary and edge case testing is performed to uncover difficult defects.

Effort Level

Sanity testing requires minimal test preparation since formal test cases are not needed, and checks are exploratory in nature.

Conversely, regression testing demands significant upfront effort to identify scope, select test cases, prepare test data, and configure environments before execution.

When Performed

Sanity testing is conducted early in development just after code changes are made as an initial checkpoint.

Regression testing occurs after sanity testing passes and provides downstream validation of bug fixes and new features before release.

Reporting

Sanity testing may involve informal bug reporting. The goal is to quickly identify “showstopper” defects.

Regression testing requires formally logging all bugs in tracking tools and rigorous adherence to processes is required.

Automation

Sanity testing can often be done manually since it focuses on user scenarios. Simple automation scripts may assist.

Regression testing is commonly automated using CI/CD pipelines for efficiency in execution and tests can be run unattended.

Sanity testing vs Regression testing Examples

Let’s look at sanity testing and regression testing examples to help illustrate the difference in their approach.

Sanity Testing Example

An e-commerce site is being modified to optimize the checkout process. After the developer commits code changes, the tester first performs a quick sanity check by:

  • Adding a shirt to their online shopping cart
  • Proceeding to checkout and selecting shipping
  • Entering payment details and submitting the order
  • Verifying they receive an order confirmation

This happy path test focuses on validating that the core checkout workflow still functions after changes.

Regression Testing Example

For the same e-commerce site, once sanity testing passes, full regression tests are executed:

  • Automated scripts verify user login still works properly
  • Test cases are run to purchase various products using multiple accounts
  • Invalid data is entered to confirm error handling
  • Order history and inventory levels are checked after orders are placed
  • Performance tests confirm response times for checkout remained the same

This rigorous regression testing goes beyond the happy path to assess whether the checkout changes did not negatively impact other parts of the system.

The narrowed sanity testing gives quick confirmation of checkout stability, while regression testing provides comprehensive validation across the entire application.

Conclusion

As iterated in this post, sanity testing and regression testing are two vital quality assurance techniques that every software tester should master.

While they serve different purposes, they work together to validate builds and uncover defects efficiently. By understanding when to utilize each approach and leveraging test automation, you can establish an optimal validation process.

Effectively applying these fundamental test types while being aware of their unique advantages enables the delivery of higher-quality software with each iteration. With this knowledge, you should now have a firm grasp of best practices for bug-catching with sanity and regression testing.

FAQs

Which Comes First Sanity or Regression Testing?

Sanity testing should be conducted before regression testing when validating application changes. The lightweight sanity checks provide quick confirmation that basic functionality works, establishing readiness for the more exhaustive regression test cycles.

By staging testing in this sequence, teams avoid wasting effort regression testing unstable builds that fail sanity validations.

Is Sanity Testing a Subset of Regression Testing?

No, sanity testing is not a subset of regression, though both are important validation steps. Sanity testing performs cursory checks on core functionality after changes, while regression testing thoroughly re-validates entire features.

David Usifo (PSM, MBCS, PMP®)
David Usifo (PSM, MBCS, PMP®)

David Usifo is a certified Project Management professional, professional Scrum Master, and a BCS certified Business Analyst with a background in product development and database management.

He enjoys using his knowledge and skills to share with aspiring and experienced Project Managers and Business Analysts the core concept of value-creation through adaptive solutions.

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