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The Role of Smoke Tests In Software Development


Split - What Is a Smoke Test

Smoke testing is an integral part of the software development lifecycle. Although the term might sound ambiguous to the uninitiated, it plays a pivotal role in delivering quality software applications. So, what exactly is a smoke test, and how does it intersect with feature flags? Finally, why should it matter to you? Read on to dive deep into the world of smoke testing and understand how it impacts feature flag management.

What Is a Smoke Test?

Smoke testing, sometimes referred to as “build verification testing”, is a preliminary testing process that validates the stability of a software build through test cases. It serves as an early warning system for identifying critical bugs or issues that could disrupt the software’s core functionalities. The term “smoke test” originates from the hardware testing process where a device passes the test if it doesn’t catch fire or “smoke” on the first switch on.

The primary goal of smoke tests is to detect severe issues early using test cases. It’s a high-level, non-exhaustive testing technique that focuses on the critical functionalities of an application rather than diving into the details. Think of it as an early stage checkpoint that a software build needs to pass before it proceeds to more rigorous, detailed testing procedures.

How Smoke Testing Works

Smoke testing is typically conducted when a new software build or version is released. The software testers will validate the key features and most important functionalities of the application – the ones the system cannot function effectively without. For instance, in an eCommerce application, testers might check if a user can successfully add items to the cart, checkout, and make a payment.

If the software build passes the smoke test, it’s deemed stable enough to proceed to the next testing phases like functional testing, integration testing, or regression testing. Conversely, if the build fails the smoke test, it’s sent back to the development team for bug fixing and improvements. Essentially, a successful smoke test can save a lot of time and effort by preventing unstable builds from entering into more detailed testing stages.

Advantages of Smoke Testing

Smoke testing, an essential part of the software development lifecycle, offers several key advantages:

  1. Quick Identification of Defects: Smoke tests are designed to quickly identify any major issues in a new build, ensuring that basic functionalities are working as expected. Smoke tests usually run quickly, providing fast feedback, unlike running more comprehensive test suites or system testing, which take longer.
  2. Early Bug Detection: Conducted early in the testing cycle, smoke testing helps in detecting critical bugs at an initial stage, preventing them from escalating into more significant problems.
  3. Time and Cost Efficiency: Being a preliminary testing phase, smoke tests save time and resources by catching major flaws before more intensive testing is conducted.
  4. Build Stability Verification: It helps in verifying the stability of a build, determining whether it is stable enough for further, more detailed testing phases.
  5. Facilitates Continuous Integration: Smoke testing is particularly valuable in continuous integration environments, as it allows for quick feedback on the health of a build, supporting rapid development cycles.
  6. Increased Confidence: By ensuring that major functionalities are working after each build, smoke testing increases confidence in the software’s reliability throughout the development process.
  7. Reduces Integration Risks: By regularly checking the key functionalities, it reduces the risks associated with integrating new code into the main codebase.

Overall, smoke testing serves as an efficient and effective method for ensuring that the most critical functions of a software application are operational, thereby facilitating a smoother and more reliable development process.

Understanding the Different Types of Smoke Testing

Smoke testing, a crucial initial step in software quality assurance, can be categorized into different types based on its application and context. Here’s a short summary of the various types of smoke testing:

  1. Build Verification Test (BVT): This is the most common form of smoke testing, performed on initial builds to ensure that the critical functionalities are working and the build is stable enough for further testing.
  2. Domain-Specific Smoke Testing: Tailored to specific business domains or industries, these tests focus on key functionalities critical to that particular domain.
  3. Automated Smoke Testing: Involves the use of automation tools to execute predefined basic tests quickly and efficiently, often used in continuous integration environments.
  4. Manual Smoke Testing: Conducted manually by testers, especially when the testing requires human observation for aspects such as usability or when automated testing is not feasible.
  5. Smoke Testing in Agile: In agile methodologies, smoke testing is frequently conducted to verify the stability of iterative builds and ensure that the most recent changes haven’t disrupted major functionalities.
  6. Component-Level Smoke Testing: Focuses on verifying the basic functionality of specific components or modules in a software application.
  7. Configuration-Specific Smoke Testing: This involves testing the application in various configurations (like different environments, databases, or hardware) to ensure basic functionality works across these variations.

Each type of smoke testing serves the purpose of ensuring that the software application is stable enough for further detailed testing, acting as a quick check to identify and eliminate major functional errors early in the development cycle.

A Little More on Automated Smoke Tests

Unlike manual smoke testing, automating smoke tests involves using software tools to automatically execute a predefined set of basic tests on a software application. This process is essential for quickly validating the stability and core functionality of a software build or subset, particularly in environments where frequent changes are made, such as in continuous integration/continuous deployment (CI/CD) pipelines. Here’s a quick summary:


  • Efficiency: Automated smoke tests are run quickly and frequently, providing immediate feedback.
  • Consistency: Ensures that the basic functionality works consistently across different builds.
  • Early Detection: Helps in identifying major issues at an early stage in the development cycle.
  • Integration: Easily integrates with CI/CD pipelines for regular and automated checking of builds.

Common Tools:

  1. Selenium: Widely used for web application testing, Selenium can automate browsers for smoke testing purposes.
  2. JUnit/TestNG: Frameworks for writing and running repeatable automated tests in Java applications.
  3. Cypress: A modern JavaScript-based tool for end-to-end testing, useful for web applications.

By automating smoke tests, teams can quickly assess the health of new builds and make informed decisions about whether to proceed with further, more comprehensive testing. This automation is a key component in modern agile and DevOps practices.

The Intersection of Smoke Testing and Feature Flags

Now that we understand smoke testing, let’s explore its relationship with feature flags.

Feature flags, also known as feature toggles, provide developers with the ability to turn certain features of a software application on or off without having to redeploy the entire application. They offer a safety net, allowing new features to be tested in production while minimizing the risk. If something goes wrong, the feature can simply be turned off using the feature flag.

Smoke testing plays a crucial role when working with feature flags. When a new feature is introduced into a system via a feature flag, smoke testing can quickly validate if the addition of this new feature disrupts any of the application’s critical functionalities. In other words, it provides an assurance that the feature flagged version of the application is ready for further testing and eventually for release.

By integrating smoke tests and feature flags, you can enhance software quality, decrease risks, and accelerate the development cycle. Smoke testing helps you ensure that new features, when turned on, will not break your application, while feature flags allow you to mitigate the potential impact if they do.

A Practical Example With Split

Let’s bring this into a real-world context with Split.

Split, an enterprise-leading feature management and experimentation platform, provides robust feature flagging, enabling you to deploy features with confidence. However, ensuring the stability and reliability of your application is still paramount, which is where smoke testing comes into play.

When you implement a new feature using a feature flag in Split, you can force the feature to be “on” (and just as easily force it to be “off”) in order to perform a smoke test to make sure your application’s key functionalities are not disrupted. If the test passes, you can confidently proceed with further testing and eventually expose the feature to your user base. If any critical issue arises, you can easily turn off the feature flag, thereby minimizing the impact on your users and your application.

Wrap Up

To wrap up, smoke testing is an essential part of the software development lifecycle, serving as the first line of defense against critical bugs and issues. When combined with feature flags, it provides an efficient, effective, and safe way to introduce and manage new features in a software application.

By understanding and correctly implementing smoke testing in your development process, you can save time, reduce risk, and improve the quality of your software applications. Integrating this with a powerful feature flag management platform like Split will take your feature delivery and management process to the next level. If you are interested in getting more info on how to set up a smoke test, we got you covered. Or if you just want to know how to better test feature flags, we have more info on that as well.

So, the next time you’re adding a new feature using a feature flag, don’t forget to perform a smoke test. It could be the difference between a successful feature launch and one that goes up in smoke 😉

Other Software Testing Methodologies for Those Interested

  1. Sanity Testing: A narrow and deep approach focused on one or a few functionalities. It’s done after minor code changes or bug fixes to ensure that the changes work correctly and don’t adversely affect related functionalities. More to come on how this differs from smoke testing.
  2. Regression Testing: This involves re-running functional and non-functional tests to ensure that previously developed and tested software still performs correctly after a change. It checks for new bugs in existing code after modifications.
  3. Automation Testing: Involves using software tools to run tests automatically, managing test data, and utilizing results to improve software quality. It’s efficient for large-scale repetitive tasks and helps in continuous integration and delivery.
  4. Acceptance Testing: This is a type of testing done to determine whether the requirements of a specification or contract are met. It’s often the final phase of testing, performed by the end users to ensure the software meets their needs.
  5. Manual Testing/Exploratory Testing: Involves testing software manually, i.e., without using any automated tools. Testers play the role of end-users and verify that all the features are working correctly. It’s important for testing user interfaces and user experience, and for cases where automated testing is not feasible.

Each type of testing has its specific use and importance in the software development lifecycle, ensuring thorough quality assurance and functionality of the software product.

Switch It On With Split

The Split Feature Data Platform™ gives you the confidence to move fast without breaking things. Set up feature flags and safely deploy to production, controlling who sees which features and when. Connect every flag to contextual data, so you can know if your features are making things better or worse and act without hesitation. Effortlessly conduct feature experiments like A/B tests without slowing down. Whether you’re looking to increase your releases, to decrease your MTTR, or to ignite your dev team without burning them out–Split is both a feature management platform and partnership to revolutionize the way the work gets done. Schedule a demo to learn more.

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