A Complete Guide to Smoke Testing in Software QA

Timothy Joseph Timothy Joseph | September 28, 2021

A Complete Guide to Smoke Testing in Software QA

The phrase “smoke test” was lifted from the construction industry. During this test, water pipelines would be filled with smoke to see if there were any leaks and other underlying issues.

In the tech industry, smoke tests were first used for hardware testing. In this test, hardware boards were tested to see whether they would smoke once they were plugged in and turned on. If they did emit smoke, they would fail the tests and were immediately unplugged. If they didn’t, they’d move on to the next round of testing.

Smoke testing plays a similar role in software development and software quality assurance — albeit without the literal smoke.

What Is Smoke Testing in Software Testing?

It is a crucial part of developing applications and quality assurance. It is the first line of defense against faulty code in initial software builds. Smoke tests aren’t used to debug builds — they are used to find out whether the builds are working in the first place.

Unlike other QA tests that are exhaustive and check the overall code, smoke tests are fast and targeted. They are used to test new builds and ensure that the core or critical functions of the written program are working properly.

If any of the key features or functions of the software aren’t working, then the build is immediately rejected or redone. Testing only the main functionalities of the software helps save time, effort, and costs. In short, smoke tests can help improve your return on investment on the product.

After all, if there is an error with the critical areas of the build, then it would be a waste of time to check its other, less important functions. It would also be a waste to continue working on the current build as well.


Features of Smoke Testing

It is also called build verification testing or build acceptance testing. The tests verify whether the main functions of the initial build are working accurately. Based on the results, the build may be accepted to the next series of QA tests or rejected altogether.

Smoke tests are sometimes also referred to as intake tests, as they decide the next round of testing.

There are several aspects involved in smoke testing. These aspects or features differentiate it from other types of QA tests.

Some of the key features of smoke testing are as follows:

  • Quick to run: Only the important features or critical functionalities of the build are tested. It usually takes only up to 60 minutes to finish a smoke test.
  • Flexible: It can be done manually or through automated processes.
  • Non-exhaustive: These tests involve a very limited number of test cases. However, they should still be capable of uncovering basic errors in new builds.
  • Broad coverage testing: Applicable to different levels of software testing, including integration testing, acceptance testing, and system testing.
  • Easy to test: Smoke tests should also be easily executed by developers to improve QA processes.

When To Perform a Smoke Test

A smoke test is performed at the beginning of the software development life cycle or SDLC process. This test should always be done with any newly completed build or release that is integrated with existing software.

As such, smoke tests are performed before any detailed regression or functional testing. By conducting smoke tests early in the SDLC, developers or QA testers can quickly verify the build quality and task execution.

Builds with any errors are quickly sent back to development before any time is wasted with tests that are more exhaustive.


How To Plan a Smoke Test

A smoke test may be manual, automated, or a mix of the two. Regardless of what type of smoke test you choose to conduct, the planning stage remains largely the same.

Here are some key tips for planning and running a smoke test:

  • Prepare for testing: Make sure to set the preferred atmosphere for the smoke test. This involves preparing any files, servers, and licenses you may need for the test. Create copies of your files and build, as well, so you have backups in case anything happens.
  • Collect all necessary files: Get all the build or code files you will need for the test.
  • Write test script: Use a single script to run the tests. Moreover, ensure that your script is written so that it creates and saves a report after each test. This way, any build failures can be properly and accurately reported to the developers.
  • Clean data: Ensure your test runs in a clean environment. Remove any extraneous files that may affect the smoke test. This also includes stopping the server and emptying database tables.

Types of Smoke Tests

There are three ways developers and QA engineers can conduct this type of testing. The type of smoke test used may depend on the builds you need to test, time constraints, or your personal preference.

  • Manual tests

    This is the most common type of testing. This method tests each initial build or any new features added to existing builds. In the manual method, you will have to modify or update your test scripts based on each test requirement. In some cases, you may need to create entirely new scripts.

  • Automated tests

    Automation smoke testing allows you to test batches of initial builds. Using an automation tool for this type of testing is ideal when you have limited time before build deployment.

  • Hybrid tests

    As its name suggests, hybrid tests are a mix of both manual and automated smoke tests. Combining the two types can boost the overall performance of the testing.


Smoke Test vs Sanity Test

Sanity testing is a subset of regression testing. Its features are very similar to smoke testing, with one key difference.

Both tests are conducted quickly and efficiently. However, a smoke test is done on a completely new build. A sanity test is done on an existing build that had new features added or functionalities that were corrected.

Sanity tests are often performed on builds that have already passed the initial smoke tests. These builds are then modified or corrected after a series of testing. As such parts of the build are already stable and only the new functionalities need to undergo QA.

Smoke Testing Sanity Testing

Checks critical functionalities or features of new builds are working fine

Checks new functionalities added to existing builds or corrected bugs

Tests basic end to end features of the system

Tests only a specific component in the system

Verifies the build or system stability before more rigorous testing

Verifies rationality and originality of the system before more rigorous testing

A subset of acceptance testing

A subset of regression testing

Often documented and scripted

Not documented and scripted

May be done on both stable and unstable builds

Only done on relatively stable builds or applications

Conducted by developers and testers

Conducted by testers or users


Advantages of smoke testing

It is a crucial part of the software development process. Preliminary testing offers numerous benefits, such as:

  • Detects bugs early in the development phase

    Conducting smoke tests early on helps you ensure the quality of your programs. You can quickly determine which builds need to go back to the drawing board.

  • Improves effectiveness of QA team

    Why waste time, effort, and manpower testing minor functions if the main purpose of the software already doesn’t perform as intended? By testing only the core functionalities of your build, you can quickly determine whether it would work as intended. This way, your QA team can move on to other projects and tests.

  • Helps make the QA process highly effective

    Uncovering obvious errors immediately saves time and effort for your QA team. It helps streamline the QA process. Additionally, it can promote confidence and job satisfaction among the QA teams.


Best Tools for Smoke Testing

There are several tools you can use to perform it. The following are two of the best and most popular tools for automated smoke tests:

  • Selenium

    Selenium is used extensively in the software testing industry as an automation tool. It is an open-source automation tool and can run using JavaScript.You can perform and receive results for up to 250 test cases within three to four hours. Tests conducted using selenium can be recorded and replayed in the same environment as the software.

  • PhantomJS

    PhantomJS is the preferred automated smoke testing tool for web applications, as long as your tests aren’t extensive. It supports several web standards and works smoothly with the development workflow. You can cut down the testing time by two-thirds using PhantomJS. Moreover, you can use this tool to perform manual testing easier, as well.



Quality assurance is a vital step during the software development life cycle. You can’t put just anybody in charge if you want to get favorable results and high-quality builds. The people in charge of your QA process need something more than training — they need experience and dedication.

That is exactly what QASource offers. We deliver high-quality QA outsourcing services to all our clients. Our team consists of the top technical talent with years of experience on the job. We work closely with our clients to provide customized solutions, time-bound delivery, and an extensive range of quality assurance services — all at affordable costs.

Further, streamline your smoke and sanity testing with our team’s expertise. Call us today at +1.925.271.5555 and learn how we can help you improve the quality of your deliverables.

Download your free checklist below and discover the steps that need to be completed when preparing for performance testing.

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This publication is for informational purposes only and nothing contained in it should be considered legal advice. We expressly disclaim any warranty or responsibility for damages arising out of this information and encourage you to consult with legal counsel regarding your specific needs. We do not undertake any duty to update previously posted materials.

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