Smoke and Regression Testing in Software Development

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Software testing

What is software testing?

While designing a software application, an essential part of the SDLC (software development life cycle) is software testing. The software testing is conducted by the QA (quality assurance) teams. It is performed on the newly developed software application to confirm that the real results are the same as the expected results. This process is used to evaluate the functionality of a software application and ensures the requirements are met to run a defect-free system.

Different types of software testing

In order to run an error-free system; software testing must be conducted on two levels, the functional and the nonfunctional.

Nonfunctional testing – This type of testing is performed to ensure the proper running of the nonfunctional aspects like performance, readability, and visibility of a software application. It is done to check whether the application is ready with aspects like speed, scalability, and reliability that are not covered in the functional testing, nonfunctional testing is:

  • Performance Testing
  • Failover Testing
  • Stress Testing
  • Maintainability Testing
  • Scalability Testing
  • Disaster Recovery Testing
  • Compliance Testing
  • Portability Testing

Functional testing – This category of testing is done to confirm that the software application is operating as per the specific requirements of its functionality such as data manipulation, processing, and defects. The following are the different types of functional testing:

  • Unit Testing
  • Integration Testing
  • System Testing
  • Sanity Testing
  • Smoke Testing
  • Interface Testing
  • Regression Testing
  • Beta/Acceptance Testing

Now let’s talk about two specific types of functional testing; Smoke Testing and Regression Testing, their utilities, functionalities and their differences.

What is Smoke Testing?

Smoke testing is the initial level of software testing performed on the just developed software build. This testing is important as it establishes the critical functionalities of a software application and confirms the smooth working of the application.

If the build passes the smoke test, then it is considered as stable and lined up for further tests. At times the build may fail to pass the smoke test, in that case, it is rejected and directed back to the developers.

Since smoke testing is the most basic form of testing; it is done prior to the actual testing series. The test is conducted using some basic test cases and is run to check the basic functions of an application whether it is running well.

What is Regression Testing?

Regression testing is done after a build is acknowledged as stable and deployed in QA setting to ensure the smooth working of the build post changes. It is mostly a sanity check essentially done to figure out any possible adverse effect caused after a change in the code. This ensures that in order to fix a defect it should not give rise to other defects or bugs in the working areas of the application. Therefore, regression testing takes place after the development of a new module, defect fixing or a change request. Sometimes a software impact analysis is also done to identify the specific areas that may have been affected after the change.

Differences between smoke testing and regression testing

  Smoke Testing Regression Testing
Test Objectives It is surface-level testing conducted to confirm the build is stable to be sent for further testing to the QA team. It is deep-level testing to detect probable defects and adverse functional effects due to changes in code. It confirms the rationality of the build to pass through more rigorous testing.
Testing Modes It can be done either manually or automated, it is always carried out before regression testing. It is carried out regularly through the testing phase and mostly automated for cost management.
Teams Involved It is usually done by developers and at times by testers depending on the release or acceptance of the build. It is only carried out by professional testers to check defects and fix bugs.
Documentations It is usually documented, then passed to smoke testing. It is not documented. The passed documents of smoke testing are used in regression testing.
Resource & Cost It does not upsurge the budget of the software but is time-consuming and exhaust resources. It is automated hence saves on time and resources but increases budget as there is an investment in test automation tools to automate the process.


Software testing is a fundamental process followed faithfully in the software development lifecycle. It is done at multiple stages by various testing methods. Amongst these, two basic testing methods are smoke testing and regression testing.

Smoke testing is used to check the initial build of the software and its stability before passing it to the QA team to perform further tests. Regression testing is conducted to detect any defects or bugs due to changes in the code of the developed build, which may affect its normal expected functioning.

Both modes of testing are essential at various stages of software development and must be followed diligently to ensure the production of premium quality software products.

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D Sarkar is a Technical Writer by profession, with a background in Comparative Literature and has been an English Language trainer. When she’s not working, she enjoys sketching, reading and cooking.

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