Comparison and Difference Analysis Smoke Test vs Regression Test

Software testing specialists use various types of tests to ensure that an application or software works as expected. Although both Smoke Tests and Regression Tests are used by testers to verify each new build of an application, they serve different purposes and are used at different stages of software testing.

If you want to understand what these tests are, how they differ, and when to use them to ensure maximum quality in your tests, you are in the right place. Let’s start by defining these two tests and then explore the differences between smoke and regression tests with a comparison table.

What is a Smoke Test?

A smoke test is used to verify the basic functionalities of a software. These tests are usually completed quickly and are used to determine if the software is ready for distribution. Smoke tests are repeated daily or at regular intervals. Developers and test engineers typically perform smoke tests.

For example, if you need to perform a smoke test for an e-commerce application, the following functions might be tested within the scope of the Smoke Test:

  • Login Function
  • Adding/removing products to/from the cart
  • Adding/removing products to/from the wishlist
  • Completing the purchase process

What is a Regression Test?

A regression test is used to verify that a feature that worked in a previous version of the software continues to work in a new version. These tests are always conducted after the software is updated with new features or bug fixes. In other words, it tests whether the changes made in the new version have any side effects on the overall software. Test engineers typically perform regression tests.

For example, let’s consider the same e-commerce application and assume the smoke test has passed. Therefore, during regression testing, the following aspects or features might be checked to ensure the new feature works well both on its own and with existing features:

  • In addition to verifying the purchase process, check if payment can be completed using all available options.
  • Verify if the privacy settings of the wishlist can be changed, whether it can be shared with others, and if items added to the wishlist also appear in normal search results.
  • When it comes to account information, check if multiple addresses can be saved, if the order history feature is validated, and if the user can download the invoice for the purchase, etc.

Comparison Table

  1. Purpose: Although these two types of tests are sometimes confused with each other due to their usage purposes, they fundamentally serve different purposes.

    • Smoke Test: The purpose of a smoke test is to verify that the most basic and frequently used functions of a software work.
    • Regression Test: Conducted after a new version or update of the software, the purpose of a regression test is to ensure that existing functionality still works correctly. It checks the effects of changes made to existing functions on other functions.
  2. Scope: These two types of tests also differ in terms of scope.

    • Smoke Test: A smoke test tests the most basic, critical, and important functions of the software.
    • Regression Test: A regression test can test all functions of the software.
  3. Timing: The application times of these two types of tests also differ.

    • Smoke Test: It starts in the early stages of the software development process and is performed at every stage. This test is used to get quick feedback.
    • Regression Test: It is conducted after the software is updated with new features or bug fixes. In other words, it is regularly applied to continuously check existing functionality.

Smoke Test

  • Conducted to check basic functions and detect major errors.
  • Performed starting in the early stages of the software development process and at every stage.
  • Generally has a narrower scope, covering basic functions.
  • Usually performed by the development team or test engineers.
  • Requires less time and manpower compared to regression testing.

Regression Test

  • Conducted after a new version or update of the software to ensure that existing functionality still works correctly.
  • Performed after every new version or update of the software. Regularly applied to continuously check existing functionality.
  • Has a broader scope, evaluating the overall impact of changes on the entire software.
  • Usually performed by test engineers.
  • Requires more time and manpower compared to smoke testing.

Author: Ebubekir Sarıgül