In software development, functional testing is a form of software testing that verifies whether a system meets its functional requirements.

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

Sometimes, functional testing is a quality assurance (QA) process.

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.

Types

Functional testing includes but is not limited to:

Sanity testing

Smoke testing

Regression testing

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

Open-source tools

Several open-source tools support functional testing across web, mobile, and API applications. These include:

• Selenium – Web browser automation

• Playwright – Cross-browser end-to-end testing

• Robot Framework – Keyword-driven automation

• Appium – Mobile application testing

• SoapUI – API functional testing

• Keploy – API testing and test generation

See also

References