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Differences Between Smoke Testing and Sanity Testing

Sanity Testing vs Smoke Testing

Software testing is an integral part of the software development lifecycle, aimed at ensuring that the software meets desired quality standards and functions as expected. It involves the systematic execution of various test cases to identify bugs, defects, or any deviations from the specified requirements.

Understanding different testing methodologies is crucial for software testers and developers alike. It enables them to select the most appropriate testing approach based on project requirements, resources, and constraints. By employing effective testing strategies, teams can detect and rectify defects early in the development process, minimizing the risk of costly errors and ensuring the delivery of high-quality software products to end-users. Additionally, familiarity with diverse testing methodologies fosters collaboration among cross-functional teams and promotes continuous improvement in their software development practices.

There are so many software testing methodologies to consider: functional testing, acceptance testing, regression testing, manual testing, and beyond. In this post, we’ll focus on the difference between smoke testing and sanity testing.

What Is Smoke Testing?

Purpose of Smoke Testing in Software Development

Smoke testing, also known as build verification testing, is conducted to quickly evaluate whether the most crucial functionalities of a software build or release are working correctly. Its primary purpose is to ensure that the basic features of the application are operational before proceeding with further testing. Smoke testing aims to identify major issues early in the development process, preventing wasted time and effort on more extensive testing if the build is fundamentally flawed.

Role in Early Detection of Major Issues

Smoke testing plays a critical role in the early detection of major issues in a new build or release. By executing a predefined set of test cases representing core functionalities, it promptly highlights any show-stopping defects or integration issues. This rapid assessment helps development teams identify and address critical issues at the outset, facilitating smoother progression to more comprehensive testing stages.

Key Characteristics of Smoke Testing

Smoke testing in software development focuses on evaluating essential functionalities and critical pathways of the application. It typically employs a small, predefined test suite that covers core features, allowing for a quick assessment of build stability. This testing approach can be executed rapidly, providing immediate feedback to development teams. Smoke testing is often conducted manually by testers or with the assistance of automated smoke tests using automation tools.

Common Scenarios

Smoke testing is conducted after integrating new code changes or features into the main branch, serving as a preliminary check to ensure the build’s stability. It is also performed before initiating more extensive testing cycles, such as regression testing or feature-specific testing, to identify any major issues early in the development process. In Agile development, smoke testing is integral to verifying that each increment of work is viable for further development, facilitating continuous integration and delivery of reliable software increments.

Automation Tools and Automated Smoke Testing

In Agile environments or projects with frequent builds, automated smoke tests are highly beneficial. Automation tools such as Selenium, Jenkins, or Cypress can streamline the execution of smoke tests, enabling rapid validation of build integrity. Automated smoke tests are designed to run automatically whenever a new build is generated, providing immediate feedback on its stability and functionality.

Further Testing

While smoke testing focuses on validating basic functionalities, further testing, such as regression testing, integration testing, and user acceptance testing, is necessary to ensure comprehensive coverage and quality assurance. Once the smoke test passes, development teams proceed with additional testing activities to verify the behavior of the software in different scenarios and environments, ensuring its readiness for release.

What Is Sanity Testing?

The Purpose of Sanity Testing

Sanity testing, also known as sanity check testing, is a type of software testing that focuses on quickly verifying specific functionalities or areas of the application after a bug fix, feature addition, or minor changes. Its primary purpose is to ensure that the recent modifications haven’t adversely affected the core functionalities of the software. Unlike comprehensive testing approaches, sanity testing is not aimed at exhaustive validation but rather at a quick evaluation of the components touched by recent work to determine if further testing is warranted.

Sanity Testing’s Role

In software development, sanity testing plays a crucial role in validating specific functionalities after a bug fix or feature addition. Once a change is implemented, sanity testing is performed to ascertain that the essential functionalities related to the recent modification are still intact and operating as expected. This targeted approach helps in quickly identifying any regressions or unintended consequences resulting from the recent changes. By conducting sanity testing, development teams can gain confidence in the stability of the modified build and proceed with more extensive testing activities if necessary.

Key Characteristics and Common Scenarios

Key characteristics of sanity testing include its focus on specific functionalities rather than comprehensive coverage, its rapid execution, and its ability to provide immediate feedback on build stability. Common scenarios for sanity testing include testing critical pathways or key user interactions affected by recent changes, verifying integration points between new and existing features, and ensuring that essential functionalities remain unaffected by minor updates or patches. Additionally, sanity testing is often employed in Agile development environments where frequent iterations and rapid deployments necessitate quick validations of software builds to maintain development momentum and ensure the timely delivery of high-quality software products.

Smoke Testing vs Sanity Testing

Origin and History

Smoke testing and sanity testing have roots in software quality assurance processes dating back to the early days of software development. Smoke testing originated as a term in hardware testing, which it referred to turning on a new piece of hardware to see if it would smoke due to electrical faults. On the other hand, sanity testing emerged as a concept to quickly verify whether changes made to software had introduced major issues. Both testing types have evolved alongside advancements in technology and the increasing complexity of software systems.

Difference in Scope

Smoke testing typically involves a broader scope, covering basic functionalities and critical pathways of the software. In contrast, sanity testing focuses on narrower and more specific areas, such as newly implemented features or recently fixed bugs. While smoke testing aims to ensure the overall stability of the build, sanity testing targets specific changes or additions.

Frequency Recommendations

Smoke tests are often run more frequently, sometimes with every new build or integration, to quickly identify major issues that could impede further testing or development progress. Sanity tests, on the other hand, are typically performed after significant changes or additions, such as the introduction of new features or bug fixes, to validate specific functionalities affected by these modifications.

Varying Depths

Smoke testing provides a shallow but broad evaluation of the software, checking basic functionalities without delving deeply into specific features. Conversely, sanity testing delves deeper into the areas impacted by recent changes, ensuring that specific functionalities or features are working as expected.

Objective Comparisons

The primary objective of smoke testing is to determine whether the build is stable enough for further testing, focusing on identifying major issues that could block the testing process. Sanity testing aims to quickly verify specific functionalities or features affected by new changes or additions, ensuring that recent modifications have not adversely affected critical aspects of the software.

Execution Time

Smoke tests are designed to execute quickly, providing immediate feedback on the overall stability of the build. In contrast, sanity tests may take slightly longer as they delve into specific functionalities affected by recent changes. However, both types of testing are intended to be executed efficiently to minimize delays in the testing process and support agile development practices.

When to Use Each


In the early stages of software development, particularly during continuous integration and deployment in a DevOps environment, smoke testing proves invaluable. It’s best suited for situations where frequent builds are generated, ensuring that each build is stable and functional enough to proceed with further testing or deployment. For instance, in a Java-based project utilizing DevOps practices, smoke testing can swiftly validate core functionalities after each integration, guaranteeing that the API endpoints function correctly and basic operations are intact.

As the software progresses and new features or bug fixes are introduced, sanity testing becomes essential for validating specific functionalities affected by these changes. This testing approach is ideal for scenarios where in-depth validation of recent modifications is necessary without exhaustive testing of the entire system. In a Java project, sanity testing might focus on newly implemented features or critical areas of the API impacted by recent updates, ensuring that these components work as intended while minimizing testing efforts.

Choosing the right testing methodology, whether it be smoke testing or sanity testing, is crucial depending on the software development phase and the nature of changes made. During the early stages or continuous integration phases, prioritizing smoke testing helps maintain the stability of the software and accelerates the feedback loop. Conversely, as the software matures and undergoes iterative improvements, integrating sanity testing allows for targeted validation of specific functionalities, ensuring that changes do not introduce regressions or unexpected behavior. Ultimately, adopting a strategic approach to testing based on the evolving needs of the project enhances the overall quality and reliability of the software product.

Feature Flags and Their Role in Testing

Feature flags, also known as feature toggles or feature switches, are a powerful tool in software engineering used to enable or disable certain functionalities within an application. They allow developers to control the visibility and behavior of features or modules, even after deployment, without altering the codebase. Feature flags are commonly implemented using libraries or frameworks that provide flexible configuration options. Their utility lies in enabling gradual rollouts of new functionalities, conducting A/B testing, or quickly turning off features in case of emergencies.

Integration of feature flags with smoke testing involves selectively activating or deactivating critical functionalities or key features using flags during the testing process. This approach ensures that smoke tests focus on essential functionalities while also providing the flexibility to test new features in isolation. For the QA team, this means faster feedback on stable builds, as they can verify the core functionalities without being impeded by changes related to new functionalities or modules.

Similarly, integrating feature flags with sanity testing allows QA teams to toggle specific features or modules affected by recent changes, ensuring that the software’s critical functionalities remain intact. By selectively enabling or disabling features using flags during sanity tests, testers can conduct in-depth validations of recent modifications without compromising the stability of the build. This approach facilitates targeted testing of new functionalities while minimizing the risk of introducing regressions or performance issues. Overall, the integration of feature flags with smoke and sanity testing methods offers numerous benefits, including safer deployments, controlled rollouts of new features, and improved flexibility in managing software changes.

Benefits and Drawbacks

Advantages of Using Smoke Testing

Smoke testing offers several benefits to the software development process. Firstly, it provides a quick check on the stability of newly integrated code changes, ensuring that critical functionalities are operational before proceeding with further testing. This helps in maintaining an efficient workflow by catching major issues early in the development cycle. Moreover, smoke testing serves as a subset of regression testing, allowing the testing team to focus on essential features without the need for comprehensive testing of the entire system. Additionally, when combined with test automation, smoke testing can be executed rapidly and repeatedly, saving time and resources. Various testing tools and tutorials are available to facilitate the creation and execution of smoke test scripts, further streamlining the process.

Advantages of Using Sanity Testing

Sanity testing provides targeted validation of specific functionalities or modules affected by recent changes, offering more in-depth insights into the software’s stability. It allows the testing team to focus on critical areas without the need for exhaustive system testing. Additionally, sanity testing is particularly useful for verifying the integration of new features or bug fixes, ensuring that the software remains stable after each iteration. When performed alongside other testing methods like performance testing, sanity testing contributes to overall quality assurance by identifying issues early in the development cycle.

Potential Challenges or Drawbacks

Despite their benefits, both smoke testing and sanity testing come with potential challenges. One drawback of smoke testing is that it may not uncover all defects or integration issues, as it focuses primarily on critical functionalities. To mitigate this, it’s essential to complement smoke testing with more comprehensive testing approaches like system testing. Similarly, while sanity testing provides targeted validation, it may overlook certain edge cases or interactions between different modules. Overcoming this challenge requires careful planning and collaboration within the testing team to ensure adequate coverage. Additionally, maintaining and updating test scripts for smoke and sanity testing can be time-consuming, especially as the software evolves. Investing in robust testing tools and continuous training through tutorials can help address this challenge and streamline the testing process. Overall, while smoke testing and sanity testing offer valuable insights into software quality, it’s crucial to balance their benefits with the need for comprehensive testing to deliver reliable and robust software products.

When it comes to overcoming the challenges of smoke and sanity testing, feature flags can be a helpful ally. Feature flags promote safer testing practices by controlling the rollout of new features in live production scenarios. They also give teams the flexibility to enable or disable code changes that bring negative outcomes. 

Conclusion

In conclusion, software testing, including methodologies like smoke testing and sanity testing, is paramount in ensuring the quality and functionality of software products. While smoke testing provides a quick assessment of critical functionalities, enabling rapid feedback and efficient workflow, sanity testing delves deeper into specific functionalities impacted by recent changes, offering more targeted validation. However, both methodologies have their challenges, such as potential oversight of defects or time-consuming maintenance of test scripts. By leveraging automation tools, tutorials, and continuous collaboration within the testing team, these challenges can be mitigated, ultimately contributing to the delivery of high-quality, stable software builds.

If you’d like to research more around smoke testing and sanity testing, please refer to the following resources:

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/blog/jest-feature-flag-testing-javascript/

/blog/top-3-feature-flag-use-cases/

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