Let’s start with the most important part, what is functional testing and what it does? This term refers to the process through which QAs determine if a piece of software is acting in accordance with pre-determined requirements. Put in simple words, functional testing makes sure that the software works as it’s supposed to, its purpose is to test each function of the software application, by providing appropriate input, verifying the output against the functional requirements.

This process involves black box testing and it is not concerned about the source code of the application.

Now, what does functional testing check exactly in software?

  • User Interface
  • APIs
  • Database
  • Security
  • Client/Server communication
  • And other functionality of the Application Under Test.

Another important fact is that functional testing can be done either manually or using automation.

As its name implies the main objective of this testing is to check the functionality of the software system and it focuses on 4 main items:

  • Mainline functions.
  • Basic Usability: It checks whether the user can navigate with ease and freely through the screens without any difficulties.
  • Accessibility.
  • Error Conditions: Usage of testing techniques to check for error conditions.  It checks whether suitable error messages are displayed.

Now the actual process follows a detailed yet simple workflow:

  1. It's paramount to settle which functionality of the product needs to be tested. This can be any of the 4 main items of functional testing main objective (Main functions, messages, error conditions, and/or product usability)
  2. Recognize test input or test data based on specified requirements
  3. Compute the expected outcomes with selected test input values.
  4. Execute test cases.
  5. Compare actual output from the test with the predetermined output values. This last step is super important because it will reveal if the system is working as expected.

In Functional Testing, there are different types of testing and these are the most important ones:

  • Unit Testing: Its primary purpose is to test each unit or function. It mainly has one or a few inputs and produces a single output.

In unit testing, code coverage is mandatory. Ensure that test cases exist to cover the following:

Line coverage

Code path coverage

Method coverage

  • Smoke Testing: this process determines whether the deployed software build is stable or not. Its a confirmation for the QA team to proceed with further software testing.
  • Sanity Testing: this is run to verify that every major functionality of an application is working perfectly, both by itself and in combination with other elements. Also, it is usually done after smoke testing.
  • Regression Testing: In this test cases are re-executed in order to check whether the previous functionality of the application is working fine and the new changes have not introduced any new bugs.
  • Integration Testing: This is done to ensure that individual modules work as expected when operating in combination with each other. The main function or goal of this testing is to test the interfaces between the units/modules. Its normally done after unit testing, once all the individual units are created and tested.
  • Beta/ Usability Testing: in this stage, actual customers test the product in a production environment. This stage is necessary to gauge how comfortable a customer is with the interface. Their feedback is taken for implementing further improvements to the code.