Functional testing

Not to be confused with Functional testing (manufacturing).

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

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

Functional testing can evaluate compliance to functional requirements.

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

Functional testing differs from acceptance testing. Functional testing verifies a program by checking it against design document(s) or specification(s), while acceptance testing validates a program by checking it against the published user or system requirements.

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.

In fixture testing, while ICT fixtures test each individual component on a PCB, functional test fixtures assess the entire board's functionality by applying power and verifying that the system operates correctly.

Types

Functional testing includes but is not limited to:

• Sanity testing, a.k.a. 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

See also

• Non-functional testing – Testing software for non-functional behavior
• Acceptance testing – Test to determine if the requirements of a specification or contract are met
• Regression testing – Checking whether changes to software have broken functionality that used to work
• System testing – Testing conducted on a complete software system
• Software testing – Checking software against a standard
• Integration testing – Type of software testing
• Unit testing – Validating the behavior of isolated source code
• Database testing – The testing of database software systems
• Security testing – The process of finding flaws in the security of information systems
• Load testing – Process of putting demand on a system and measuring its response
• Test automation – Use of special software to control test execution and analysis