Difference between regression, sanity and smoke tests

 Difference between regression, sanity and smoke tests: 

Regression Testing, Sanity Testing, and Smoke Testing are all types of software testing methodologies, each serving distinct purposes within the software development lifecycle. Here's how they differ:

1. 1. Smoke Testing:

   • Purpose: Smoke Testing is performed to ensure that the most critical functionalities of the software are working correctly after a new build or release.
   • Scope: It focuses on verifying that the basic and essential features of the application are functional and stable enough to proceed with further testing.
   • Execution: Smoke tests are typically brief and straightforward, covering only the main functionalities. They are executed early in the testing process to quickly identify major defects or issues.
   • Outcome: If the smoke test passes, it indicates that the build is stable enough for further testing. If it fails, it suggests fundamental problems that need immediate attention before proceeding with more in-depth testing.
   • Frequency: Smoke tests are often run on every new build or release.
   • Example: In an e-commerce application, smoke testing may involve verifying that users can successfully log in, view product listings, and add items to the shopping cart.

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3. 2. Sanity Testing:

   • Purpose: Sanity Testing, also known as Sanity Check, is performed to quickly evaluate whether specific areas of the software have been fixed or modified correctly after changes or enhancements.
   • Scope: It focuses on testing specific functionalities or areas of the application that have been recently modified or impacted by changes.
   • Execution: Sanity tests are more targeted and selective compared to smoke tests. They are designed to cover only the areas that are relevant to the recent changes.
   • Outcome: If the sanity test passes, it indicates that the recent changes have not introduced any critical issues, and the modified functionalities are working as expected.
   • Frequency: Sanity tests are typically run when there are minor changes or updates to the software, ensuring that the core functionalities remain intact.
   • Example: After implementing a new payment gateway in an e-commerce application, sanity testing may involve verifying that users can successfully complete transactions using the new payment method.
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4. 3. Regression Testing:

   • Purpose: Regression Testing is performed to ensure that recent code changes or enhancements have not adversely affected existing functionalities or introduced new defects.
   • Scope: It involves retesting the entire application or a significant portion of it, including both modified and unaffected areas, to detect any regressions or unintended consequences of changes.
   • Execution: Regression tests are comprehensive and cover a wide range of test cases, including functional, non-functional, and integration tests.
   • Outcome: If regression tests pass, it indicates that the recent changes have not caused any unexpected issues, and the software behaves as expected. If regressions are found, they need to be addressed and fixed before the release.
   • Frequency: Regression tests are typically performed after every significant code change, bug fix, or system update to ensure that the software remains stable and reliable.
   • Example: In an e-commerce application, regression testing may involve retesting various functionalities such as user authentication, product search, checkout process, and order management after implementing new features or fixing defects.

In summary, Smoke Testing evaluates the overall stability of the software after a new build, Sanity Testing verifies specific areas impacted by recent changes, and Regression Testing ensures that existing functionalities remain intact after modifications. Each type of testing serves a unique purpose in maintaining software quality and stability throughout the development lifecycle.