Testing Basic Interview Questions : What Is Functional Testing Explain It with Example?

What Is Functional Testing Explain It with Example?

Functional testing means testing the application against business requirements. Functional testing is executed using the functional specifications given by the client or by the design specifications according to use cases given by the design team. Role of functional testing is to validating the behavior of an application.

Functional testing is more important because it always verifies that your system is fixed for release. The functional tests define your working system in a useful manner. In functional testing tester has to validate the application to see that all specified requirements of the client whatever we have said in SRS or BRS have been incorporated or not.

Functional testing is always concentrating on customer requirements and whereas the Non-Functional testing is always concentrating on customer expectations.

Functional and Non Functional Test Cases

Functional test cases target business goals and non functional test cases target performance, resource utilization, usability, compatibility etc. Functional testing is a part of system testing.

Example of functional testing is explained below

Considering example if you are functionally testing a word processing application, a partial list of checks you would perform minimally includes creating, saving, editing, spell checking and printing documents.

Types of Functional Testing

Functional testing falls in to two categories:

1. Positive functional testing: - This testing carry exercising the application’s functions with valid input and also verifying that the outputs are correct.


Again continuing with the word processing example, a positive test for the printing function might be to print a document containing both text as well as graphics to a printer that is online, filled with paper and for which the correct drivers are installed.

2. Negative functional testing: - This testing involves exercising application functionality using a combination of invalid inputs, some unexpected operating conditions and by some other “out-of-bounds” scenarios.


Again continuing with the word processing example, a negative test for the printing function might be to disconnect the printer from the computers while a document is printing.

What probably should happen in these scenarios are a plain-English error message displayed, informing the user what happened and instructing him/her on how to fix the problem.

At last we conclude that in functional testing functionality of the module is tested and structure is not considered. It is performed, based on user's perspective. These tests ensure that the system does what users are expecting it to do.

This type of testing means testing the functionality example include input the proper data and checking the output as per the requirement documents.


  1. Great Wonderful Answer!!

  2. This was wonderful explanation! thank you

  3. I was having a chat with my friend who is a beginner in testing. He was sharing his problem with me on how to initiate testing. Although there are many books and articles on theories and concepts of testing but there is no help or information available on how to start testing and how a tester should proceed with the same. This is one excellent article you put together.

    also if you do not mind here is another article which talks about the basic steps of functional testing:

    Basic steps of Functional Testing

    Hope this will also help.


  4. Explanation was good and i need some more examples

  5. very nicely explained, thank you!

  6. So apparently it it's not testing a specific function? All this time I've not been applying to certain jobs thinking I didn't qualify... :)

  7. Good for a KG kid.. Love it..

  8. thankyou sir... very nice... :)

  9. Explanation was good............thank you

  10. Thanks for sharing..:-)

  11. it ws good explanation but still need more example.....

  12. Thank u for sharing. Simple and clear language :)

  13. Thank you for wonderful explanation.
    But I have a doubt, What type of risks or issues can be in functional testing?

  14. functional testing should ensure software application/product quality by providing measures for the following factors:


  15. This is really helpful concise and informative.

  16. Awesome explanation very simple way thanks

  17. nice explanation
    but i need some more
    1.when we go for functional testing ?
    2.why functional testing required ?

  18. Dear nandita...It is purely based on customer requirements. .

  19. Awesome explanation...... thanks for providing & please keep going.....

  20. Awesome explanation very simple way thanks

  21. very explanations sir .....Myself Tamilmaran software manual tester IT Aerospace

  22. very nice... good explanation :)