Regression, Sanity & Smoke Testing

Regression, Sanity & Smoke testing are three additional methodologies of testing. These are not necessarily distinct from Unit and Integration tests, rather they contain Unit and Integration tests.

Smoke Testing

Smoke Testing is an early form of testing, which aims to check for the critical functionalities of the application. The name "Smoke Testing" comes from the "Smoking Machine" analogy. If a machine is smoking when turned on, then there's something wrong with it. It is performed in the initial build though not necessarily after each build.

Smoke Testing can possibly involve unit and integration tests, however, the tests usually are too minor or vague to be considered as either. It usually includes practices like checking if the application runs successfully without any unexpected crashes, the pages load correctly, the navigation and form buttons are functional etc.

Regression Testing

Regression means "Return to a previous or less advanced state". Regression Testing simply checks if the newer changes to the application have somehow damaged the older features or not. This usually involves re-executing the previous test cases after the introduction of every update.

Sanity Testing

Sanity Testing, also known as Build Verification Testing (BVT) can be considered a subset of Regression Testing. It also involves writing unit and integration tests to make sure that the newer changes have not broken the older features, however, the scope of testing in this case is narrow as the tests are focused only on the part of the application where the new changes have been introduced. While in Regression Testing, the tests are spread over the entire application.

After every new build, Sanity Testing introduces some new test cases. These test cases automatically become a part of the Regression Tests in the later builds, since Regression Testing includes re-executing all the previous test cases to ensure that the older features are working correctly.

Since Regression Testing and Sanity Testing can be very repetitive, tedious and not cost-efficient, therefore they are rarely performed manually and hence, are usually a part of automation testing.