January 20, 2020

What Is Smoke Testing In Software QA Testing?

The term smoke test originated from the practice of construction workers injecting smoke into water pipelines to validate that they do not leak, which helps avoid floods. In the context of technology, the phrase smoke test comes from hardware testing. A new board is plugged in, and the power is turned on. If there is smoke coming from the board, the power is turned off and testing is ceased.

In the software realm, smoke testing checks the core functionality of a program to ensure the program is ready for further testing. This prevents a QA team from attempting to run a full test of software that can’t complete basic functions.

Smoke testing in technology is now broadly used to test product features in a limited time. If key features don’t work, or if key bugs haven’t been fixed, testing is ceased so that further time is not wasted installing or testing the build. Fixing the identified issues becomes the programmer’s top priority.

Smoke testing is essentially a subset of all defined and planned test cases that cover the main functionality of a component or system. The testing ascertains if the most crucial functions of a program work, but the testing does not bother with the finer details. Some of the capabilities tested during the smoke test phase include accessing the application, logging in with a set of users (admin, regular user), and checking the main modules of a particular application.


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When Is Smoke Testing Conducted?

Smoke testing is a process to make sure the build received from the development team is testable. It is often called a “Day 0” check and it is conducted at the build level. A smoke test can also be run as part of the build process in concert with a more thorough test when the build is a release candidate.

Work begins when the GUI interface and database are stable. Additionally, smoke testing is often conducted when new basic functionality is added to a system. But, this is not an exhaustive test such as unit or regression testing.

Sometimes a smoke test is not enough to test a change in detail when working on a module, especially when using new code. Running a smoke test with each build does not remove the responsibility from developers to test their changes before submitting them to the repository. Developers should run the smoke test manually before committing a change.

The image below depicts how smoke testing works.

How smoke testing works in software development


The Purpose and Importance of Smoke Testing

The main purpose of smoke testing is not to find bugs in the software but rather to let the system test team know what their starting point is. Smoke testing provides a goal for the developers and lets them know when they have achieved a degree of stability. The trick to establishing a good smoke test is to create a group of tests that are broad in scope, as opposed to depth.

Smoke tests disqualify bad builds at a low cost, making it easier to cope with frequent (e.g. daily) builds. Smoke tests are often automated and standardized from one build to the next. They test things that are expected to work, and if they don’t, it may mean the program was built with the wrong file or that something basic is broken. A smoke test is most useful for bug fixes and for looking for inadvertent interactions between existing and new functionality.

Characteristics of Smoke Testing

  • Runs quickly (the measure of “quickly” depends on the specific situation).
  • Enables self-scoring, as any automated test should do.
  • Provides broad coverage across the system.
  • Can be run by developers as well as part of the quality assurance process.
  • Exposes basic errors in a new build, though it need not be exhaustive.

Advantages of Smoke Testing

  • Minimizes integration risks.
  • Improves the quality of the end-product.
  • Uncovers functional errors as well as architectural and component-level design defects.
  • Helps diagnose errors.
  • Simplifies corrections by associating tests with incremental new builds and rebuilds.

Who Can Do Smoke Testing?

The smoke test is an important part of the deployment process, so the test team should be aware of the application features that are at the core of the business functionality. The person in charge of the smoke testing should also be able to test every module of the application.

After performing the smoke testing, the tester should also be able to approve or reject the deployed build. In cases where the build is rejected, the tester should provide feedback to the development team and process the information efficiently.

The Automation of Smoke Testing

To build a smoke test, the test team first determines which parts of the application make up the high-level functionality. The team then develops automated procedures for testing the major parts of the system.

In this context, refers to the basic operations that are used most frequently. These operations can be exercised to determine if there are any small or large flaws in the software.

Examples of major functions include logging in, adding records, deleting records, and generating reports. Smoke tests may also comprise a series of tests to verify the database points to the correct environment, the database is the correct version, sessions can be launched, all screens and menu selections are accessible, and data can be entered, selected and edited.

When automating tests, the smoke test should be the first series of tests to automate. Smoke testing through automation is a huge benefit and value to customers as well as a time and cost control for businesses. Build verification tests are added to the library of reusable scripts, and performing a smoke test may require 1-2 days.

When testing the first release of an application, the test team may want to perform a smoke test on each segment of the system. This enables test development initiation as soon as possible without waiting for the entire system to become stable.

What Is Sanity Testing?

Smoke testing is sometimes confused with sanity testing. However it is different. A smoke test is done first and does not go further than that. Sanity testing is done during the release phase to check the main functionalities of the application without going deeper. Sanity testing is is also a subset of regression testing.

As an example of how sanity and smoke testing compare, in a project’s first release, a development team releases the build for testing. The test teams then test the build. Smoke testing involves testing the build for the first time in order to accept or reject the build.

If the test team accepts the build, then the build goes on for further testing. Imagine the build has three modules: Login, Admin, Employee. The test team tests these main functionalities of the application without going deeper. This is sanity testing.

Smoke Testing Is a Critical Step

The smoke test is an important part of the testing process cycle and must not be skipped in any release. The smoke test identifies issues so that they can be fixed before proceeding.

Sacrificing the quality of smoke testing could have negative consequences that affect users and impact the business model. If the application is not able to allow users to complete simple actions, like accessing the application or logging into the application, they may look for an alternative, and that leads to a business losing a customer—something nobody wants.

Additionally, if the application is for internal operations, it can stop or delay business operations until the development team is notified and able to work on the fix. Smoke testing reduces rework and avoids in-depth testing of a system that is not stable.

Smoke testing is just one example of how testing is woven through all of 3Pillar Global’s product development processes. Contact 3Pillar Global today to learn how we can help.