Functional Testing – A Complete Guide!


“Optimism is an occupational hazard of programming; feedback is the treatment.” – Kent Beck

As Kent Beck quote suggests feedback is important in the same way functional testing is vital for software improvement. This blog will dive in to understand completely about what is functional testing, types of functional testing and non-functional testing. So let’s begin!!

What is Functional Testing?

Functional Testing is a type of software testing that substantiates the software system against active requirements or specifications. The goal of Functional tests is to test each function of the software application, by giving relevant input, assessing the output against the functional requirements.

Functional testing primarily involves black box testing and it is not anxious about the source code of the application. This testing reviews User Interface, APIs, Database, Security, Client/Server communication and other functionality of the Application Under Test. The testing can be accomplished either manually or using automation.

Types of Functional testing

Let’s look at the list and explanation of types of functional testing given below:

  1. Unit Testing
  2. Smoke Testing
  3. Sanity Testing
  4. Integration Testing
  5. Beta/Usability Testing 
  6. Regression Testing

Unit Testing

Unit testing is usually executed by a creator who composes various code units that could be associated or unrelated to attain a specific functionality. This usually involves writing unit tests which would call the procedures in each unit and assess those when the crucial parameters are passed, and its return value is as expected.

Code coverage is a significant part of unit testing where the test cases require to occur to cover these three coverages given below:

  1. Line coverage
  2. Code path coverage
  3. Method coverage

Sanity Testing 

Testing that is accomplished to confirm that all the important and critical functionalities of the application or system are working accurately. This is commonly done after a smoke test.

Smoke Testing

Testing that is done after each structure is broadcasted to check to assure build or structure stability. It is also hailed as build verification testing.

Regression Testing

Testing conducted to ensure that putting new code, improvements, fixing of bugs is not smashing the existing functionality or resulting in any instability and still functions according to the specifications.

Regression tests require not to be as substantial as the real functional tests but should ensure only the amount of coverage to ensure that the functionality is stable.

Integration Tests

When the system depends on many functional modules that might individually work flawlessly, but have to function coherently when gathered together to obtain an end to end scenario. The confirmation of such scenarios is called Integration testing.

Beta/Usability Testing

When a product is exposed to the real consumer in a production like an atmosphere and they test or check the product. The user’s satisfaction is developed from this and the feedback is taken. This testing is also identical to that of User Acceptance testing.

Best types of functional testing availabe in 2020

What do you test in Functional Testing?

The chief objective of Functional testing is testing the functionalities of the software system. It particularly focuses on –

  1. Mainline functions:  checking the crucial functions of an application
  2. Basic Usability: It includes basic usability testing of the system. It checks whether a user can voluntarily navigate through the screens without any problems or not.
  3. Accessibility:  Checks the availability of the system for the user.
  4. Error Conditions: Usage of testing techniques to check for error situations.  It checks whether suitable error messages are exhibited or not.

How to do Functional Testing?

Let’s look at a step by step process on how to do Functional Testing :

  1. Understand the Functional Requirements
  2. Recognize test input or test data based on requirements
  3. Evaluate the usual outcomes with selected test input values
  4. Implement test cases
  5. Compare real and computed expected results

Now let’s have a glimpse on what is non-functional testing.

Non Functional Testing

Non-functional testing is the testing of a software application for its non-functional needs like the way a system governs, preferably than particular behaviours of that system. This is in distinction to functional testing, which tests against functional requirements that illustrate the functions of a system and its elements. 

Functional Testing

The terms of various non-functional tests are frequently used interchangeably because of the extension in scope between many non-functional requirements. Here’s an example to understand it better like the term software performance is a wide term that involves multiple certain requirements like dependability and scalability. Now let’s look at the types of Non-functional testing.

The types of non-functional testing are:

  1. Performance Testing
  2. Load Testing
  3. Volume Testing
  4. Stress Testing
  5. Security Testing
  6. Installation Testing
  7. Penetration Testing
  8. Compatibility Testing
  9. Migration Testing

Functional Testing Tools

Here is a list of outstanding functional testing tools. Below is the explanation as follows: 

  1. Selenium – It is a popular Open Source Functional Testing Tool
  2. QTP – A very user-friendly Functional Testing tool by HP
  3. JUnit- It is used particularly for Java applications and this can be utilized in Unit and System Testing too
  4. soapUI – It is an open-source functional testing tool, primarily used for Web service testing. It supports many protocols such as HTTP, SOAP, and JDBC.
  5. Watir – It is a functional testing tool used for web applications. It benefits tests implemented at the web browser and tries a ruby scripting language

From beginning to deployment, the software or application undergoes numerous types of testing by testing teams and developers. The end purpose of all the efforts is to provide a working software/app that satisfies users’ requirements and the client’s intentions. Both the teams become so knowledgeable with the application that they probably become a victim of tunnel vision. They are completely aware of workarounds and may miss certain scenarios which might be vital for end users.

The users are innocent about how the application works. They are more concentrated on ‘How the application should function?’ They use the application with a new mind and whether it is spontaneous to follow or not. UAT is organized on user stories and establishes how well it fulfils their requirements. Users do not utilize the ‘Test to Break’ approach while doing user acceptance testing. Instead, UAT is a measure of how favourable your application performs in natural scenarios. 

In Software Testing, Functional testing is a technique of testing functionalities of the system and assures that the system is functioning as per the functionalities specified in the business document. The purpose of this testing is to examine whether the system is functionally excellent or not!!!