What is Functional Testing?
Functional Testing is a form of testing performed for estimating the quality of a software product by verifying the features provided by the application with respect to client-requirement documentation. Before the start of software development, the requirement gathering team comes up with different sets of documents like Software Requirements Specification (SRS), Business Requirements Specification (BRS), Customer Requirements Specification (CRS), and Functional Testing is one measure to make sure whether all the documented requirements have been met & implemented as a part of the final product.
The ‘test results’ are compared with the ‘expected results’ and based on the output/result, a particular functional testing is considered as ‘Pass/Fail’. Since it is a part of black-box testing, a test engineer well-versed with black-box testing methodologies can perform functional testing as well.
Importance of Functional Testing
As discussed earlier, a tester acquainted with functional testing has to validate the software product from all angles and make sure that the requirements are well documented. Also, different requirement specification documents should be met in the product/application under test. Hence, functional testing is performed by the tester where the product is tested more from a customer/consumer point of view i.e. ‘customer requirements’, unlike Non-functional testing is performed by giving priority to ‘customer expectations’. We would look into the difference between Functional testing & Non-functional testing in subsequent sections.
Functional Testing With Example
Now, for instance we will consider some test factors to keep in mind while performing functional testing with example cases mentioned above.
- Screen testing: Allow a new user to sign-up using the sign-up page. A ‘returning’ user should be able to log-in using existing credentials and ‘Forgot Password’ feature should be in place in case the user does not remember the password. Performing the functional testing of example scenario, the team should test the ‘Sign-up & Sign-In’ page with different user/password combinations and record the output. They need to make sure that the navigation between screens is fast and features (listed in SRS) for this page are implemented.
- Feature testing: Based on the target market, the product team & development team would have identified the ‘potential browsers & devices’ on which the application should be fully-functional with respect to browser compatibility testing. To validate this scenario we perform ‘browser compatibility testing’ where the application is tested on a combination of different devices (desktops, mobiles, tablets, etc.), Operating Systems (Windows, Linux, Android, iOS, KaiOS, etc.), and Browsers (Firefox, Chrome, Opera, etc.).
As Functional testing involves verification of the functionalities implemented in the product, the test team has to make sure that every ‘feature’ is tested. This also includes covering error scenarios and boundary conditions. Manual testing has its own set of limitations since you may need a bigger test team if your product has a huge number of features. This will increase the overall expenses. You may not be able to achieve best ‘test coverage’ if you only use manual testing and your QA might reject your product if it does not meet the necessary ‘coverage guidelines’.
Automated Functional testing can come in handy in scenarios where your project is under extremely tight deadlines. It improves the overall productivity of the employees since they are engaged in more ‘interesting work’ and the organization can save time & cost.