Understanding the Differences: Smoke Testing vs Functional Testing Testlio July 5th, 2024 Quality and functionality are critical factors in software development. This is where testing methodologies like smoke testing and functional testing come into play. Smoke testing is a high-level, preliminary testing process to ensure that a software program’s most critical functions are working correctly. In contrast, functional testing is a more detailed and thorough testing process. Although both types of testing aim to ensure that software meets expectations, they differ in scope, depth, and stage in the software testing lifecycle at which they are conducted. This blog post will provide an in-depth comparison of smoke testing and functional testing, providing insights into their unique roles in software development. Is Smoke Testing The Same As Functional Testing? Smoke and functional testing verify that the software functions as expected. Both testing types consider the user’s perspective, with functional testing deeply analyzing user interactions and smoke testing providing an initial check to ensure that key functionalities are operational. Additionally, both types of testing can be automated to increase efficiency and accuracy. Both are essential parts of a comprehensive testing strategy. Therefore, smoke testing vs functional testing shows that while both types of testing aim to identify issues in the system, smoke testing is a broad, shallow approach used to verify the stability of the system, whereas functional testing is a deep, narrow approach used to verify the functionality of specific components of the system. Smoke Testing Smoke testing is a high-level, non-exhaustive testing process that doesn’t go into the details of every function but checks if the critical functionalities are working fine. Originating from hardware repair, smoke testing verifies that your app doesn’t “catch on fire” or have any app-breaking issues the first time you run it. Smoke tests are often the first step in the software testing process, performed before more detailed testing such as functional, integration, and system testing. The main reasons to conduct smoke testing are: Early Detection of Major Issues: Smoke testing helps identify and fix major issues early in the software development lifecycle. This can save time and effort in the later stages of development. Verification of Critical Functions: This ensures the software’s critical functionalities work as expected. It is crucial before the software is subjected to more rigorous and detailed testing. Build Stability: Smoke testing helps determine a software build’s stability. If a build passes the smoke test, it’s usually considered stable and ready for further testing. Functional Testing Functional testing is a type of software testing that validates the software system against the functional requirements/specifications. The purpose is to check whether your product meets your intended specifications. This testing mainly involves black box testing, and it is not concerned with the application’s source code. Functional testing is typically conducted after smoke testing and integration testing in the software testing lifecycle. The main factors to consider when deciding to perform functional testing include: Requirement Verification: Functional testing should be performed when there is a need to verify that the software functions according to the specified requirements. Detailed Testing: When more detailed and thorough testing of the software is required, functional testing should be performed. Functional testing offers several benefits, such as ensuring software meets all specified requirements, enhancing user experience by evaluating the software from a user’s perspective, and identifying bugs before release. However, it has limitations, including a focus solely on functionality, potentially missing non-functional issues like performance, and failing to catch bugs in scenarios not covered by the initial requirements. Smoke Testing vs Functional Testing Testing Type Smoke Testing Functional Testing Definition Smoke testing is a high-level type of testing conducted to check if the basic functionalities of an application are working fine. Functional testing is a type of testing which verifies that each function of the software application operates in conformance with the requirement specification. Objective The main objective is to validate the stability of the system in order to proceed with more rigorous testing. The main objective is to check the functionalities of the software system. Depth This is a shallow and wide approach to the application. This is a deep and narrow approach to the application. Timing This is typically done when the software is at the initial development stage. This is typically done after smoke testing. Execution This can be done either manually or using an automated tool. This can also be done either manually or using an automated tool. Time and resources It requires less time and resources. It requires more time and resources. When To Perform Smoke Testing Smoke testing and functional testing are performed at different stages of the software testing lifecycle, and the decision to execute them depends on various factors. Smoke testing is typically performed when a new build is released or after significant changes have been made to the existing functionality. The main factors to consider when deciding to perform Smoke testing include: New Build or Major Update: Whenever a new build or major update is released to the software, smoke testing should be performed to ensure that the critical functionalities are working as expected. Time Constraints: Smoke testing is a quick and efficient way to test software when time is limited. It helps identify major issues early in the development process. On the other hand, functional testing is performed to verify that each function of the software application operates in conformance with the requirement specification. Factors to consider when deciding to perform functional testing include: Requirement Verification: Functional testing should be performed when there is a need to verify that the software functions according to the specified requirements. Detailed Testing: When more detailed and thorough testing of the software is required, functional testing should be performed. In different scenarios, these tests can be applied as follows: New Software Release: Smoke testing should ensure the critical functionalities are working when new software is released. Once the software passes the smoke test, functional testing can be performed to verify the software functions in more detail. Software Update: When software is updated, smoke testing should be performed to ensure that the update has not broken any critical functionalities. If the software passes the smoke test, functional testing can be performed to verify the new functionalities added by the update. Continuous Integration: In a continuous integration environment, smoke testing can be performed automatically whenever a new build is created. The build can be deployed for functional testing if it passes the smoke test. Practical Example: Banking Application When the development team has prepared the first build of the banking application after completing unit and integration testing, the first step is to perform Smoke Testing. The smoke test cases for this scenario might include: User Registration and Login: Confirm that users can register and log in using their credentials. Account Balance Check: Check if users can view their account balance. Fund Transfer: Verify that users can transfer funds to another account. If these core functionalities pass the smoke test, the application is stable enough for further testing. Next, functional testing is performed. This is a more detailed and thorough testing process that deeply covers all the software functions. For the banking application, functional testing might include: Bill Payment: Verify that users can pay bills through the application. Scheduled Payments: Check if users can schedule future payments. Transaction History: Confirm that users can view their transaction history. In this way, smoke testing is used as a preliminary check to identify any major issues early in the development cycle, verifying the build’s stability for further testing. Once the build passes the smoke test, functional testing is performed to verify the new functionalities added by the update. Final Thoughts A comparison of smoke testing vs. functional testing shows crucial differences in the lifecycle of software testing. Smoke Testing is a high-level, preliminary testing process that verifies the software’s critical functionalities. In contrast, Functional Testing is a more detailed and thorough testing process that checks all the software functions according to the specified requirements. However, it’s important to remember that these are not the only testing methodologies available. Exploratory testing, for instance, is another valuable approach that allows testers to simultaneously learn, test, design, and refine their understanding of the software under test. It’s a context-driven testing technique that encourages creativity and intuition in the testing process. If you’re interested in learning more about exploratory testing and how it can add value to your software testing process, visit Testlio’s exploratory testing solutions.