Smoke Testing vs. Sanity Testing

Anushree Chatterjee

Software testing is all about making sure a program works the way it’s supposed to. But there are many ways to test software, depending on what aspect you want to examine. You can use a combination of these approaches, like functional testing, non-functional testing, regression testing, smoke testing, sanity testing, and so on, to find and fix bugs. Being able to differentiate between these approaches and then using them to complement one another is a must.

Two types of testing that often cause confusion for testers are smoke testing and sanity testing. Each has its own benefits and challenges, and hence, you must know them well enough to leverage them.

What is smoke testing?

Smoke testing, also known as “Build Verification Testing“, is a type of software testing that determines whether the deployed build is stable enough to proceed with further testing. The idea is to verify that the key functionalities are working and the build is not “broken”. If the smoke test fails, the build is rejected to save time and costs involved in more detailed testing.

Benefits of smoke testing

Here are the benefits that you can see when you do smoke testing:

• Early bug detection: Smoke testing helps identify critical bugs early on in the development process. This is crucial because fixing bugs later in development can be significantly more expensive and time-consuming. By catching major issues early, smoke testing prevents testers from wasting effort on a build with fundamental flaws. Read: Minimizing Risks: The Impact of Late Bug Detection.
• Improved software quality: Smoke testing paves the way for higher-quality software by identifying and resolving major issues early. A stable build allows for more focused and efficient testing throughout the development process.
• Reduced risk of failure: Smoke testing acts as a gatekeeper, ensuring builds are functional enough to proceed with further testing. This helps mitigate the risk of major failures later in development or even after release.
• Faster development cycles: Smoke testing can help streamline the development process by catching critical issues early. Developers can address problems quickly, and testers can focus their efforts on more thorough testing of a stable build. Understand What is SDLC? The Blueprint of Software Success.
• Better resource management: Smoke testing helps optimize resource allocation. Resources can be directed toward more in-depth testing efforts by preventing testers from spending time on fundamentally flawed builds.
• Early progress indication: Smoke testing provides a quick indication of development progress. If the core functionalities work as expected, it shows the software is on the right track.

Challenges of smoke testing

Smoke testing also poses some challenges like:

• Limited scope: Smoke tests only cover core functionalities, so there’s a chance of missing minor bugs or issues in less critical features. It’s like a quick glance over a test instead of a deep dive.
• False sense of security: A successful smoke test might create a false sense of security, potentially leading to less focus on later stages of testing. It’s important to remember that smoke testing is just the first step.
• Maintenance: Smoke tests need to be maintained and updated as the software evolves. This can add extra work for testers, especially for complex projects.
• Manual effort: Smoke testing is often performed manually, which can be time-consuming for large projects. Automating smoke tests can help, but creating and maintaining automated tests takes effort as well.
• Definition of “smoke”: What constitutes a critical function can be subjective. Determining the scope of a smoke test can lead to debates and potential gaps in testing coverage.

How to do smoke testing?

Smoke testing involves a quick and focused approach to assess a software build’s basic functionality. Here’s how you can conduct smoke testing:

Step 1: Planning and preparation

• Identify core functionality: Define the essential features that absolutely must work for the software to be usable for further testing. This might involve reviewing requirements documents or consulting with developers.
• Choose test cases: Select a minimal set of test cases that effectively cover the core functionalities. Focus on high-level checks that validate core workflows. Read: Which Tests Should I Automate First?
• Prioritize speed: Smoke testing should be quick, ideally taking no more than 30 minutes to an hour to complete. Read: Parallel Testing: A Quick Guide to Speed in Testing.

Step 2: Test execution

• Manual or automation: Smoke testing can be done manually or with automated tools. Manual testing allows for human observation and quick turnaround, while automation can save time on repetitive tasks in larger projects. Here is a Test Automation Playbook.
• Run the tests: Execute the chosen test cases and record the results (pass/fail).

Step 3: Evaluation and reporting

• Analyze results: Identify any failed tests and assess their severity. Critical failures that block further testing need to be addressed promptly.
• Report findings: Communicate the smoke test results clearly to developers and other stakeholders. This might involve a simple report or a quick discussion highlighting critical issues.

Tips to improve smoke testing

Here are some additional tips for effective smoke testing:

• Repeatability: Smoke tests should be repeatable and ensure consistent results across different environments.
• Maintain smoke tests: Update smoke tests as the software evolves to reflect new functionalities and ensure continued effectiveness.
• Integration with CI/CD: Consider integrating smoke tests into your Continuous Integration/Continuous Delivery (CI/CD) pipeline to automate testing with every new build. These Continuous Integration and Testing: Best Practices might help you.
• Target regressions: If you have a history of recurring bugs, add targeted smoke tests to specifically check those areas to prevent regressions.
• Leverage automation: Automate repetitive smoke tests to save time and free up testers for more exploratory testing. Focus on automating core functionalities with high stability requirements.

What is sanity testing?

Sanity testing is a close cousin to smoke testing but with a slightly different focus. It is performed to verify that a specific section of the application is still working after a minor change. Sanity testing often happens after smoke testing and before more in-depth regression testing.

Benefits of sanity testing

Benefits of doing sanity testing include:

• Early detection of regressions: Sanity testing focuses on areas where changes were made, making it ideal for catching regressions (bugs introduced by new code). This helps ensure new features or bug fixes haven’t broken existing functionalities.
• Faster feedback loop: By quickly checking the impact of changes, sanity testing creates a faster feedback loop between developers and testers. Developers can address issues promptly before they snowball into larger problems.
• Improved test efficiency: Sanity testing helps testers focus their efforts. By verifying core functionalities around changes, they can avoid wasting time on in-depth testing of areas not affected by recent modifications.
• Increased confidence in builds: A successful sanity test can boost confidence that the latest build is stable enough for further testing. This helps reduce anxieties and allows testers to proceed with a clearer sense of the software’s health.
• Reduced risk of integration issues: Sanity testing can help identify integration problems early on. By checking how changes in one part of the software interact with others, testers can prevent major roadblocks during the integration testing phase.
• Cost-effectiveness: Sanity testing is a relatively inexpensive approach compared to more comprehensive testing methods. By finding critical issues early, it can save time and resources in the long run. Know How to Save Budget on QA.

Challenges of sanity testing

Sanity testing also comes with its set of challenges:

• Limited scope: Sanity testing focuses on recently changed areas, which means it might miss bugs in untouched functionalities. It’s like checking a specific room after a renovation, but the rest of the house remains unexamined. Read Test Planning – a Complete Guide.
• Unscripted and manual: Sanity testing is often unscripted and performed manually. This can lead to inconsistencies in testing procedures and potential for human error.
• Definition of “sanity”: Determining what constitutes a “sanity” check can be subjective. What one tester considers crucial might differ from another’s perspective, leading to gaps in test coverage.
• Focus on functionality only: Sanity testing primarily checks core functionalities and may not delve into non-functional aspects like performance or usability. Other testing methods are needed for a well-rounded evaluation.
• Maintenance overhead: As the software evolves, sanity test cases need to be updated regularly to reflect changes. This can add extra work for testers, especially for complex projects.

How to do sanity testing?

Here’s how you can go about performing sanity testing:

Step 1: Preparation

• Identify changes: The first step is to understand what has changed in the software build. This could involve reviewing code commits, bug fixes, or new features implemented.
• Define scope: Based on the identified changes, determine the scope of your sanity testing. Focus on areas where modifications were made and potentially related functionalities that could be impacted.
• Design test cases: Create a set of lightweight test cases that specifically target the functionalities impacted by the changes. Keep them simple and focused on core functionality checks. Know How to Write Test Cases? (+ Detailed Examples).

Step 2: Test execution

• Manual or automation: Sanity testing can be done manually or with automated tools. Manual testing allows for quick checks and flexibility, while automation can save time on repetitive tasks in larger projects. Read how testRigor is a Test Automation Tool For Manual Testers.
• Execute the tests: Run the designed test cases and record the results (pass/fail). Pay close attention to any unexpected behavior or deviations from expected functionality.

Step 3: Evaluation and reporting

• Analyze results: Evaluate the test results and identify any failures. Analyze the severity of failures and prioritize critical issues that block further testing.
• Report findings: Communicate the sanity test results clearly to developers and other stakeholders. This might involve a simple report or a quick discussion highlighting critical regressions. Read Test Reports – Everything You Need to Get Started, to know more about reporting.

Tips to improve sanity testing

Following these tips can make your sanity testing endeavors fruitful:

• Repeatability: Ensure your sanity tests are repeatable and produce consistent results across different environments.
• Maintain test cases: Keep your sanity test cases up-to-date as the software evolves to reflect new changes and maintain their effectiveness.
• Risk-based prioritization: Don’t just test everything that has changed. Analyze the potential impact of changes and prioritize critical areas or functionalities with a higher risk of regression.
• Leverage historical data: If you have historical data on bugs or areas prone to regressions, use that information to inform your sanity testing focus.
• Partial automation: Consider automating a subset of core sanity tests that are frequently executed. This frees up testers for more exploratory or complex testing while ensuring consistent checks for critical functionalities. Know How to Automate Exploratory Testing with AI in testRigor.
• Usability checks: If feasible, include some basic usability checks within your sanity testing process. This can help identify any glaring usability issues introduced by recent changes.

Analogy to differentiate between smoke and sanity testing

Imagine you own a car, and you take it to a mechanic for regular maintenance or because a warning light appears on the dashboard. In this situation, smoke and sanity testing will look something like this:

Smoke testing

• Scenario: You get your car back from a full service, where multiple parts might have been replaced or updated (like brakes, oil change, air filters).
• Testing approach: Before taking a long drive, you perform basic checks to ensure the car is drivable. You start the engine, check the brakes briefly, make sure the lights work, and see if the car rolls forward without strange noises. This is akin to smoke testing, where you’re checking the most fundamental functionalities of the car to ensure no major faults were introduced during the service.

Sanity testing

• Scenario: You specifically asked the mechanic to fix the air conditioning because it wasn’t cooling properly.
• Testing approach: When you pick up the car, instead of checking everything, you directly turn on the air conditioning to see if it’s now cooling properly, ensuring that the recent fix addresses the issue without causing new problems. This is similar to sanity testing, where you focus on verifying just the functionalities affected by the recent changes to confirm everything is functioning as expected.

Smoke testing vs. sanity testing

testRigor for automated testing

By now, you must have guessed that there are aspects of smoke and sanity testing that can be automated. To do so, you need a test automation tool that is not only easy to use but also easy to maintain test cases with. One of the best options available in the market is testRigor. This tool uses generative AI to make test case creation easy, allowing you to write all kinds of test cases in plain English language or any other natural language. Here is an article to understand Transitioning from Manual to Automated Testing using testRigor.

Along with easy test case creation, speedy and negligible test maintenance can be achieved, again thanks to testRigor’s use of AI. Basically, testRigor is an AI Agent intelligent enough to test even LLMs. Read How to Automate Testing of AI Features.

Testing across various platforms and browsers is easy through this tool, as it offers simplistic English commands to perform actions and verifications of scenarios like email testing, 2-factor authentication, file uploading, database testing, and more. This will help you cover those “smoke” or “sanity” worthy test scenarios with ease.

Besides this, you can do much more with this tool, perform web, mobile, desktop, and API testing using only testRigor. Take a look at testRigor’s complete feature set.

Conclusion

Both sanity and smoke testing are crucial; smoke testing ensures overall usability, while sanity testing confirms the effectiveness and precision of recent fixes or changes. When done correctly, it can make your QA endeavors effective and efficient. Add automated testing to this mix and you’re product will be in ship-shape.

Additional resources

• What is Smoke Testing in Software QA?
• Smoke Testing vs Regression Testing – Key Differences You Need to Know
• Functional Testing Types: An In-Depth Look
• Different Software Testing Types
• Test Planning – a Complete Guide
• Test Strategy Template
• Minimizing Risks: The Impact of Late Bug Detection
• The QA Professional’s Guide to Managing Production Bugs
• Test Automation Tool For Manual Testers

Frequently Asked Questions (FAQs)

The term originates from hardware testing, where a device is first powered on to see if it smokes or fails immediately. In software, it similarly tests whether the build “catches fire” upon initial use.

Yes, smoke testing is often automated to quickly assess the stability of a software build. Automation helps in rapidly verifying that the application does not crash and can perform its primary functions.

If a build fails smoke testing, it is typically rejected and sent back to the development team for fixes before it is tested further. This helps in saving time and resources on testing unstable builds.

The outcome of sanity testing is determining whether the sections of the application that were affected by recent changes are still functioning correctly without introducing new bugs.

“We spent so much time on maintenance when using Selenium, and we spend nearly zero time with maintenance using testRigor.”

Keith Powe VP Of Engineering - IDT