Smoke Testing vs Sanity Testing – Software Engineering

Smoke Testing vs Sanity Testing are two essential software testing methods used to verify application stability and detect defects early in the development process. Both are quick ways to test an application, but do they test the same thing? Let us understand how they work, when to use each of them, and how they can help to improve the quality of the software in less time. In the following sections, we will explore the key differences between smoke testing and sanity testing in detail.

What is Smoke Testing?

Smoke testing is a testing method that is done to make sure that the basic parts of a software application are working properly. It is the first test done after any new version or module of the software is created. It is also known as Confidence Testing.

Smoke testing is used:

• To check that the software is stable.
• To save time, it does not test the broken software in detail.
• To catch the major problems in the software early.

For example, on a shopping website, after a new build is deployed, you can perform smoke testing by checking the following:

• Can you open the website?
• Can you log in?
• Can you search for a product?
• Can you add a product to the cart?

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What is Sanity Testing?

Sanity testing is a quick check done after small changes or error fixes to make sure that the changes work correctly. It is usually performed when there is not enough time for full testing, and the goal is to quickly verify that everything works correctly and makes sense.

Sanity testing is used to:

• Confirm that a specific function or bug fix is working.
• Ensure the new change has not impacted other parts of the app.
• Decide if the build is ready for further testing.

For example, on a shopping website, the developer fixed a bug where the “Apply Coupon” button was not functioning. Now, in sanity checking, you can check the following:

• Is the “Apply Coupon” button working now?
• Is the correct discount being applied?

Sanity Testing vs Smoke Testing

Below are the key differences between sanity testing and smoke testing.

1. Scope

• Sanity Testing is narrow and focuses only on the specific part of the application where the changes were made, and does not look at the whole system. The main goal of sanity testing is to check that the recent changes work properly and haven’t broken anything nearby.
• Smoke Testing is wide and covers core features of the application, which ensures that everything is working at a basic level. The main goal of the smoke testing is to check that the entire build is stable enough for deeper testing later.

2. Purpose

• Sanity Testing checks quickly for a bug fix or a small update that has to work as expected and has not caused any problems. It is usually done when time is short and only a few things need to be verified.
• Smoke Testing checks that the overall software build is stable, so that further testing can be performed, and it is the first step after receiving a new build from developers.

3. Level of Testing

• Sanity Testing is very focused and limited, as it only tests a few parts of the application where the changes were made, mainly logic, data flow, and correctness of bug fixes.
• Smoke Testing is broad as it covers all the key areas of the application, but does not go into detail like code complexity and performance.

4. When It is Done

• Sanity Testing is done after a bug is fixed or a minor change in the code is made to make sure the change in the software works correctly.
• Smoke Testing is done after a new build of the software is created, as before doing any detailed testing, like a quick check of the basic functions, like launching the app, logging in, or opening key pages.

5. Test Documentation

• Sanity Testing is sometimes informal, as it does not require any written test cases or any detailed planning.
• Smoke Testing can be formal or semi-formal, as it follows a basic set of written test cases, and the results are often recorded to confirm that the build passed or failed the smoke test.

6. Test Coverage

• Sanity Testing covers only a small section of the application, i.e., mainly the updated modules of the application, and not the related features.
• Smoke Testing covers most of the core functionalities of the application, but at a basic level, to confirm that they run without major issues.

7. Time Required

• Sanity Testing takes less time because it only focuses on a small section of the app.
• Smoke Testing takes more time than sanity testing, as it has to check more parts of the application.

8. Performed By

• Sanity Testing is usually performed by the testers who know bugs or recent changes, as they know exactly what needs verification.
• Smoke Testing can be performed by the developers or testers.

Key Characteristics of Smoke Testing

Below are the characteristics of smoke testing.

1. Quick and Basic Check: Smoke testing tests all the main features of the software quickly, without going into detail.

2. Fast and Simple: Smoke testing can be done manually or with the help of tools, which takes only a few minutes.

3. First Step After a New Build: Smoke testing is the first test that is done when a new version of the software is built.

4. Catches Big Problems Early: Smoke testing helps us to find big issues at the early stage of the software build, so they can be fixed before doing more detailed testing.

5. Also Called Confidence Testing: Smoke testing is also known as Confidence Testing because it shows whether the software is good enough to continue testing.

Advantages of Smoke Testing

Below are the advantages of smoke testing.

1. It saves time, as it checks if the main features of the software are working fine or not.

2. It can find big issues early and helps to find the main problems in the software after a new module is built.

3. It builds confidence, as once the smoke tests are passed, the developers and testers feel confident that the software is stable for more testing.

4. It is quick and easy to run, because they can be done manually or with the help of automated tools in just a few minutes.

5. It improves the build quality of the software, as problems are found at the early stage, due to which the overall quality of the software build improves.

Disadvantages of Smoke Testing

Below are the disadvantages of smoke testing.

1. It only checks the basics of the application and the main features of the software, and misses the hidden errors.

2. Smoke testing is not enough on its own, and it needs other tests to check that everything is working properly.

3. Smoke testing is a quick test, i.e., it only checks some part of the software that is changed, due to which many parts of the software are not tested at all.

4. It can be misleading, as if smoke tests pass, people may think that everything in the software is working fine, but still, the problems can be present in the software.

5. It needs to be updated often because if there are many changes in the software, you have to do the smoke testing many times, which can take extra time.

Key Characteristics of Sanity Testing

Below are the characteristics of sanity testing.

1. Focused and Specific: Sanity testing only checks the parts of the software that are changed, and not the whole application.

2. Fast and Targeted: Sanity testing is short and simple to test, and it saves time and effort.

3. Done After Minor Changes or Fixes: Sanity testing is mainly performed when a bug is fixed or a small update is made to check if the software fix works properly.

4. No Need for Detailed Test Cases: Sanity testing is done without creating any documents or plans.

5. Helps Decide Next Steps: Once the sanity testing is done, the software can further move to full testing.

Advantages of Sanity Testing

Below are the advantages of sanity testing.

1. It saves time as it only checks that the recent updates are working correctly, not the whole application, which takes less time.

2. Sanity testing focuses on what matters, i.e., it checks only the updated part of the software, which avoids unnecessary testing.

3. It is simple, easy to perform, and does not need detailed planning to see what has to be tested, and can be done manually in most cases.

4. Sanity testing helps to find the issues quickly, as it is short, it can catch important errors early in the process.

5. It quickly checks that the bug that was fixed before solves the problem correctly.

Disadvantages of Sanity Testing

Below are the disadvantages of sanity testing.

1. It has limited coverage because it only checks a specific part of the software that was updated and may miss bugs in other parts of the software.

2. It cannot be a replacement for full testing, as it only tests some part of the software.

3. It follows an informal process and is usually not well-documented or planned, which can lead to odd or unexpected results.

4. Sanity testing depends on the tester’s understanding, since it is done without detailed test cases, it depends a lot on how well the tester understands the changes.

5. There is a risk of missing bugs in sanity testing because it does not test the whole system; some hidden bugs might get missed.

In simple words, Smoke vs Sanity Testing helps decide whether the build is ready for deeper testing.

Which testing is performed first, Smoke or Sanity?

Smoke testing and sanity testing can be used together. Smoke testing is performed first, and sanity testing is done later.

First, smoke testing is done when a new update to the software is ready. It quickly checks if the main parts of the application are working or not. If the basic functions like opening the app, logging in, or viewing a page are working fine, the build is considered stable. After that, if a change or bug fix was made in the application, sanity testing is done, which checks a small part of the application to make sure that the fix is working fine and nothing else is broken.

After understanding Smoke Testing vs Sanity Testing, let’s explore how both differ from regression testing.

What is Regression Testing?

Regression testing is a type of software testing done to make sure that existing features of a software application are working properly after new changes, updates, or bug fixes. This testing is mainly needed when the developer makes any change in the code, i.e., fixing a bug, adding a new feature, or improving the performance.

For example, we have a website with features, User Login, Profile Update, and Logout. Now, the login module is not allowing some valid users to log in, and developers have to fix a bug in the login module. After fixing the bug, testers perform regression testing to check that all the modules are working correctly now. Although the change was made only in the login part, the testers rechecked the other related modules to ensure nothing else broke.

Sanity Testing vs Regression Testing

Below are the key differences between sanity and regression testing.

Conclusion

In summary, understanding the difference between Smoke Testing vs Sanity Testing is essential for efficient QA processes. Both Smoke vs Sanity Testing methods help teams find critical issues early and improve the stability of each software build. The smoke testing is performed when there is a new update in the software. If the updates are fine, then the sanity testing is performed to check that a small change or bug fix in the code is working fine and has not caused any new problems. And both tests help us to save time, catch issues early, and make sure the software is ready for more detailed testing.

Useful Resources:

• What is Software Testing?
• Different Types of Software Testing
• How to Become a Software Tester?
• Software Testing Interview Questions and Answers

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