Functional testing verifies that each function of the software operates in required specification. Functional testing shows “What the system does”. The goal of this testing is to check whether the system is functionally perfect.
In the execution of functional testing these steps are considered to be taken:
- Preparation of test data based on the specifications of functions
- Business requirements are the inputs to functional testing
- Find out of output of the functions based on functional specifications;
- The execution of test cases
- Observe the actual and expected outputs.
In general there are two approaches to fuctional testing:
- Requirements Based Testing : indicates strict accordance with the defined requirements.
- Business Process Based Testing : accords with the knowledge based on the day-to-day business use of the system.
Functional testing advantages:
- Functional testing simulates actual system environment and software runtime.
- It is executed in different conditions respecting real users environements (Such as for different operating systems and for different screen sizes.)
- No system structure assumptions are made while providing functional testing.
- It is easy to do manual testing.
Functional testing limitations:
- There is the high possibility of redundant – unneeded – testing.
- Logical errors in software could be missed while providing functional testing.
It is easy to find and use tools for functional testing. The most well-known are: Selenium (both web and desktop application), Robot Framework, Appium, Robotium (Android app), Linux Test Project, JUnit, Sprinter by Hewlett Packard Entreprise (manual testing), Browserstack (both automated and manual testing), Usersnap (manual testing).