Smoke Testing vs. Regression Testing: Key Differences

Jun 29, 2023 | Best Practices, Best Practices, Test Automation Insights

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Smoke and regression testing are essential processes in the overall software development process. You need both to ensure the stability and quality of your final product. However, there are vital distinctions between these techniques that any development or testing professional should understand. This guide is designed to help you understand the fundamental differences between smoke testing vs. regression testing and to apply that knowledge to robotic process automation. 

Understand Smoke Testing and Regression Testing

Testing is a crucial element of the software development lifecycle (SDLC). It represents an opportunity to discover any errors or bugs that could affect the functionality of your software. Test automation processes also help mitigate risks associated with the development process. You can locate and resolve defects early before they make their way into production. 

But what is regression testing or smoke testing? Below you will find an exploration of smoke vs. regression testing and when each applies. 

Definition and Purpose of Smoke Testing

Smoke testing, also called verification testing, focuses on checking critical functionality in an application. It determines whether the software is stable enough to perform more extensive testing. You typically use software smoke tests after completing a new build or making significant platform changes. 

The primary purpose of software smoke testing is to ensure that developers have put all critical features in place and that key functions work as intended. Smoke testing lives up to its name in that it highlights any issues or showstoppers that would bring testing to a halt. Think of it as a filter that captures any defects or failures before you go forward with more detailed testing scenarios. 

Applications that make it past smoke testing should be stable enough to allow for other testing methods, including regression scenarios. If critical issues are found, you should discontinue testing until they are resolved.

Definition and Purpose of Regression Testing

Regression testing looks for any defects introduced because of changes or enhancements made to a software build. The goal is to ensure that all previous functionality continues to operate as intended after any developer modifications. 

One of the biggest differences between smoke and regression testing is the depth of testing. You’re pushing beyond the generic “happy” path and looking at every potential scenario that could arise. For a regression testing example, consider changing an eCommerce application to add updated payment options for customers. Your regression testing would check the original and updated payment choices. 

Regression testing gives you additional time to resolve any issues arising from software changes. You ensure the developer didn’t compromise any original functionality or introduce new risks to the process. After making updates, a successful regression testing process offers additional reassurance to stakeholders that the software build works as intended. 

Overview of When and How Smoke Testing and Regression Testing Are Performed

Smoke testing and regression testing happen at different stages of the SDLC. Because smoke testing functions as a safety net to capture significant defects, it occurs at the start of testing, immediately after a new build or major change. You can also use smoke testing as a checkpoint before moving forward with more detailed regression testing. 

Smoke testing looks at the critical functions of an application. You also address specific high-level testing scenarios and basic operations. Tests should be carried out quickly and identify any big issues that would bring your testing process to a standstill. 

Regression testing should occur anytime you significantly change or enhance the software. It should also happen after you implement a bug fix. Make sure you go through all areas affected by your updates. You can perform regression testing multiple times throughout the SDLC, especially when using Agile methodology. 

Objectives and Scope of Smoke Testing

Let’s look at some key objectives you want to accomplish during smoke testing. 

  • Verify basic functionality — Smoke testing is a surface-level test. If you click a button or execute an RPA, it should operate as intended. If something goes wrong, you immediately pull back from further testing to address the problem. 
  • Detect potential failures — Your smoke testing should capture areas with functionality issues. If you see an automation failing to enter data into all fields of an online form, that’s a sign that the application is not ready for more detailed regression testing. Smoke testing allows you to avoid spending time testing software that’s not ready for prime time. 
  • Mitigate risk — Smoke testing reduces your risk of potentially allowing an unstable software build to pass onto subsequent testing phases or end-users. You can avoid critical production failures, user dissatisfaction, and business process disruptions. 
  • Save on resources — Passing on unstable builds earlier in the testing process keeps testers from spending time conducting detailed testing. 
  • Build confidence — Smoke testing allows you to provide stakeholders with preliminary confirmation that a software build passed initial functionality tests. After passing that initial checkpoint, you can reassure them that the application is secure enough for more rigorous testing.

Objectives and Scope of Regression Testing

Below are some of the key objectives to cover when performing regression testing

  • Ensure stability after changes — Every change a developer introduces brings the potential of a new bug or the breakdown of original functionality. Regression tests, usually executed using an automated testing platform, confirm whether the application operates as intended after introducing modifications. 
  • Find defects — Regression tests help you locate regression defects that occur after applying a software fix. You should look for any unintended side effects of making changes to an application, including performance degradation or compatibility issues with other systems or software. 
  • Validate fixes — Make sure any fixes applied to repair software defects are successful and haven’t caused new issues. You should be able to verify the resolution of previously detected problems and a lack of negative impacts on other software areas. 
  • Stop reoccurring defects — Regression tests help ensure you don’t see the same defects cropping up after a change. You need to validate the robustness of any fixes and feel confident that the issues won’t reemerge after the software’s release. 
  • Verify change impacts — Review the impacts of any changes to existing functionality, dependencies, or features. 
  • Ensure compliance — Ensure the new software product or RPA application complies with industry standards or regulations. For example, you may want to ensure that new automation doesn’t introduce risks to customer data privacy that might violate laws like the California Consumer Privacy Act (CCPA).
  • Maintain quality — Going over functions tested in previous phases helps ensure an application’s overall quality and stability. 
  • Support CI/CD — Agile and DevOps environments deal with frequent releases throughout continuous integration and delivery. Regression testing helps ensure that changes introduced in an iteration don’t produce regression defects that affect the software’s constancy. 

Effective regression testing helps you detect major bugs early in the testing process to avoid late-game fixes that could delay project delivery. 

Key Differences Between Smoke Testing and Regression Testing

As we discussed, smoke testing vs. regression testing differs primarily in scope and frequency. Understanding key differences and utilizing automated platforms make it easier to follow best testing practices for both. 

Focus and Purpose of Each Testing Type

Smoke testing usually focuses on surface functionality. You’re trying to assess whether the application is ready for a more robust testing process that covers more expansive scenarios. Meanwhile, regression testing focuses on functionality following major changes or updates. It tends to be more robust, focusing on both previous and current functionality. 

Timing and Frequency of Execution

Smoke testing happens at the beginning of testing, while regression testing occurs every time there’s a major change or update. Once an application passes a smoke test, additional smoke tests should not need to be completed down the line. On the other hand, regression testing can occur quite frequently, as it should be completed any time updates occur.  

Expected Outcomes and Impact on Release Decisions

Smoke testing helps you identify defects early in the process. You should look for critical failures that stop testing. Finding and repairing issues early saves costs and reduces the impact of those errors on subsequent development and testing phases. You also lower your risk by keeping unstable software builds from going through later testing phases. 

Regression testing confirms that any fixes or changes made to an application have not impacted its overall functionality. After putting it through various scenarios other than the happy path, you should ensure the build is stable. The goal is to ensure that build modifications have caused no adverse effects. 

When it comes to smoke testing vs. regression testing, both are essential elements of testing. Any product that can’t survive the rigors of both processes should not make its way to users. Both represent an opportunity to address any issues that could impact the usability of an application once it’s released for general use. 

Stop Manual Testing and Automate Your Testing Strategy

Using a test automation platform for smoke and regression testing reduces the amount of manual work on testers. Ranorex provides everything needed to help you ensure the validity of your software products. Find out more about our products by reaching out to one of our RPA experts or by exploring our automated testing tools today. 

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