Software Testing 101

Functional Testing

September 18, 2018

Functional Testing is a software testing approach that evaluates all features/functions of the software to ensure that each component operates in conformance with the requirement specifications. Each functionality or component of the application is tested in-depth to verify that the output/result provided by each application function is as desired.

How does functional testing work?

Functions are tested by feeding input and verifying the output to check what the system does. The testing may involve checking of APIs, database, security, user interface, client/server applications and functionality of the Application Under Test. The internal structure, code, performance, and environmental factors are typically not considered in Functional Testing.

At first, each component is tested to confirm its desired output and behavior and then re-checked to ensure the integrity of the rest of the system with regards to the output of this particular element. It is important to cover all possible cases of impact including edge case and boundary case scenarios.

The purpose of functional Testing is primarily to ensure usability, accessibility and requirement specs testing.

Needless to say, Functional Testing is crucial for the quality of the software. It verifies that a product or application will function properly and optimally for the users.

There are two common approaches or perspectives to implement:

  1. Requirements focused testing: This perspective prioritizes the requirements in the order of risk criteria to evaluate the most critical and important features first.
  2. Business-process focused testing: It relies on the knowledge of end-user requirements to review the application’s performance based on typical use cases and business goals.

There are many testing methods. The two primary techniques are white box testing and black box testing although any of the following are often used:

  • Unit testing
  • Smoke testing
  • User acceptance testing
  • Integration testing
  • System integration testing
  • Localization testing
  • Regression testing
  • Globalization testing

Why Functional Testing ?

All testing strategies need Functional Testing at their core. Functional verification should be a continuous process during the development cycle and through production. It ensures that:

  • End-user requirements are met
  • Application development goals are fulfilled
  • Regulatory and compliance requirements are met
  • Identifies incorrect specification
  • Finds initialization errors
  • Looks for interface errors
  • Also finds termination errors

Top Functional Testing Tools

  • Selenium
  • Telerik Test Studio
  • HPE Unified Functional Testing 
  • Sahi
  • TestComplete.
  • TestingWhiz


Functional Testing is invaluable to ensure the smooth and flawless operation of the product or application. To quote the Forrester Wave Report on Functional Test Automation “Functional Testing is one of the most crucial, time-consuming, and expensive steps in continuous testing — so it’s necessary to automate this testing, and to automate it at higher levels than most Agile teams achieve today.”

Functional Testing test cases, their execution, and results can be better managed using Test Management tools like QMetry Test Management, HPE ALM, Qtest, etc. QMetry Test Management is a comprehensive testing solution providing full test automation, quality metrics and analytics.

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