Functional testing explained

Functional testing should not be confused with Functional testing (manufacturing).

In software development, functional testing is a form of software testing that verifies whether a system meets its functional requirements.^{[1] [2]}

Generally, functional testing is black-box, meaning the internal program structure is ignored (unlike for white-box testing).^[3]

Sometimes, functional testing is a quality assurance (QA) process.^[4]

As a form of system testing, functional testing tests slices of functionality of the whole system. Despite similar naming, functional testing is not testing the code of a single function.

The concept of incorporating testing earlier in the delivery cycle is not restricted to functional testing.^[5]

Types

Functional testing includes but is not limited to:

Usability testing

Six steps

Functional testing typically involves six steps

1. The identification of functions that the software is expected to perform
2. The creation of input data based on the function's specifications
3. The determination of output based on the function's specifications
4. The execution of the test case
5. The comparison of actual and expected outputs
6. To check whether the application works as per the customer need

Notes and References

1. ISO/IEC/IEEE 24765:2017, "Systems and software engineering — Vocabulary", International Organization for Standardization, Geneva, Switzerland, 2017.
2. Book: ISO/IEC/IEEE International Standard - Systems and software engineering. ISO/IEC/IEEE 24765:2010(E). 2010. vol., no., pp.1–418, 15 Dec. 2010.
3. Kaner, Falk, Nguyen. Testing Computer Software. Wiley Computer Publishing, 1999, p. 42. .
4. Prasad, Dr. K.V.K.K. (2008) ISTQB Certification Study Guide, Wiley,, p. vi
5. Web site: Full Stack Testing . 2022-09-08 . www.thoughtworks.com . en-US.