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{{Short description|Testing software functionality}}
{{distinguish|Functional testing (manufacturing)}}
{{More citations needed|date=December 2010}}
{{Software development process}}

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 testing|black-box]] meaning the internal program structure is ignored (unlike for ''[[white-box testing]]'').<ref name="KanerFalkNguyen1999">Kaner, Falk, Nguyen. ''Testing Computer Software''. Wiley Computer Publishing, 1999, p. 42. {{ISBN|0-471-35846-0}}.</ref> 

Functional testing can evaluate compliance to functional [[requirement]]s.<ref>{{Cite book|title=ISO/IEC/IEEE International Standard - Systems and software engineering|publisher=ISO/IEC/IEEE 24765:2010(E)|year=2010|pages=vol., no., pp.1–418, 15 Dec. 2010}}</ref> 

Sometimes, functional testing is a [[quality assurance]] (QA) process.<ref name="Prasad">Prasad, Dr. K.V.K.K. (2008) ''ISTQB Certification Study Guide'', Wiley, {{ISBN|978-81-7722-711-6}}, p. vi</ref>

Functional testing differs from [[acceptance testing]]. Functional testing ''[[Verification and validation (software)|verifies]]'' a program by checking it against design document(s) or specification(s), while acceptance testing ''[[Verification and validation (software)|validates]]'' a program by checking it against the published user or system requirements.<ref>Kaner, Falk, Nguyen 1999, p.&nbsp;52</ref> 

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 (computer programming)|function]].

The concept of incorporating testing earlier in the delivery cycle is not restricted to functional testing.<ref>{{Cite web |title=Full Stack Testing |url=https://www.thoughtworks.com/en-us/insights/books/full-stack-testing |access-date=2022-09-08 |website=www.thoughtworks.com |language=en-US}}</ref>

== Types ==

Functional testing includes but is not limited to:<ref name=KanerFalkNguyen1999 />
* [[Sanity testing]], a.k.a. [[Smoke testing (software)|smoke testing]]
* [[Regression testing]]
* [[Usability testing]]

==Six steps==
Functional testing typically involves six steps{{Citation needed|date=December 2010}}

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

==See also==
{{div col|colwidth=40em}}
* {{Annotated link|Non-functional testing}}
* {{Annotated link|Acceptance testing}}
* {{Annotated link|Regression testing}}
* {{Annotated link|System testing}}
* {{Annotated link|Software testing}}
* {{Annotated link|Integration testing}}
* {{Annotated link|Unit testing}}
* {{Annotated link|Database testing}}
* {{Annotated link|Security testing}}
* {{Annotated link|Load testing}}
* {{Annotated link|Test automation}}
{{div col end}}

== References ==
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[[Category:Software testing]]