QA Essentials: Functional Testing

Dulmini Attanagoda
4 min readMay 19, 2022

Let’s understand the concept of Functional Testing in the QA field.

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Functional testing, often known as black-box testing, is a sort of testing that validates any type of software system against all functional requirements or specifications. The primary goal of functional testing is to test each of the software application’s functionalities by giving all of the proper inputs and also confirming the software system’s output against all of the specified functional requirements. Which ensures that a system’s core function operates as planned by all of its requirements.

How to do Functional Testing?

  1. Understand the functional requirements.
  2. Create test cases.
  3. Produce input test data according to the specifications.
  4. Determine the expected result.
  5. Execute the test cases.
  6. Compare the actual results with the expected results.

Types of Functional Testing

Unit Testing

Unit testing is the process of testing each unit or an individual component of a software program. It is the initial stage of functional testing. The main goal of unit testing is to validate unit components based on their performance. The goal of unit testing is to ensure that isolated code is accurate. A unit component is a single function or line of code in the program. The white box testing technique is commonly used for unit testing and is typically performed by developers.

Integration Testing

After unit testing, the second step of the software testing process is integration testing. Units or individual components of the software are tested in groups during this testing. The integration testing level’s goal is to uncover flaws through the interaction of integrated components or units. The purpose of integration testing is to ensure that all components communicate correctly.

System Testing

System testing is the process of validating the entire and fully integrated software product. A system test is used to examine the end-to-end system requirements.

Regression Testing

Regression testing is a type of black-box testing. It is used to ensure that a code update in software does not affect the product’s existing functioning. Regression testing ensures that the product functions properly with new functionality, bug patches, or changes to current features.

Smoke Testing

Smoke testing is known as Confidence testing or Build Verification testing. Which is used to determine whether the new build is ready for the next phase of testing, or if the new builds need to be stable first.

Sanity Testing

Sanity testing is a type of Software Testing performed after receiving a software build, with minor changes in code, or functionality, to ascertain that the bugs have been fixed and no further issues are introduced due to these changes. The goal is to determine that the proposed functionality works roughly as expected. If the sanity test fails, the build is rejected to save the time and costs involved in more rigorous testing.

Usability Testing

Usability testing ensures that the system is simple to grasp and utilize, even for less technologically adept users. It is frequently carried out by real users in a staging environment or as part of beta testing. The feedback from users guides future code updates.

Acceptance Testing

Acceptance testing is a type of formal testing that is performed based on user requirements and function processing. It determines whether or not the program meets the defined and user criteria. It is carried out as a type of Black Box testing, with the needed number of users participating in testing the system’s acceptability level. It’s the fourth and last stage of software testing.

Functional Testing Tools

Selenium web driver -Selenium is the most widely used automation tool. This free testing framework works with a variety of browsers and languages.

QTP -HP’s Functional Test Tool is a very user-friendly tool.

JUnit -This is mostly used for Java applications, although it may also be used in unit and system testing.

NUnit -NUnit is a free and open-source unit testing framework for.NET languages.

TestLink -TestLink is a test management solution that may be integrated into a variety of ways. It’s a free and open-source operating system with both basic and complex capabilities.


  • In this article, we mainly focused on understanding the concept of Functional Testing.
  • We also discussed different functional testing tools in the end. Let’s focus more on these tools in the future.

Thank you for reading 🎉✨