10 Difference Between Functional And Non-Functional Testing

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Software testing is a process of identifying the correctness of software by considering its all attributes (Reliability, Scalability, Portability, Re-usability, Usability) and evaluating the execution of software components to find the software bugs or errors or defects.

Software testing provides an independent view and objective of the software and gives surety of fitness of the software. It involves testing of all components under the required services to confirm that whether it is satisfying the specified requirements or not. The process is also providing the client with information about the quality of the software.

What Is Functional Testing?

Functional Testing is a type of software testing that validates the software system against the functional requirements/specifications. The purpose of Functional tests is to test each function of the software application, by providing appropriate input, verifying the output against the Functional requirements. 

Functional testing mainly involves black box testing and it is not concerned about the source code of the application. This testing checks User Interface, APIs, Database, Security, Client/Server communication and other functionality of the Application under Test. The testing can be done either manually or using automation.

Functional testing also called as black-box testing, because it focuses on application specification rather than actual code. Tester has to test only the program rather than the system.

Examples of Functional Testing Types

  • Unit testing
  • Smoke testing
  • User Acceptance
  • Integration Testing
  • Regression testing
  • Localization
  • Globalization
  • Interoperability

What do you test in Functional Testing?

The prime objective of Functional testing is checking the functionalities of the software system. It mainly concentrates on –

  • Mainline functions:  Testing the main functions of an application
  • Basic Usability: It involves basic usability testing of the system. It checks whether a user can freely navigate through the screens without any difficulties.
  • Accessibility:  Checks the accessibility of the system for the user
  • Error Conditions: Usage of testing techniques to check for error conditions.  It checks whether suitable error messages are displayed.

What You Need To Know Functional About Testing

  • Functional testing is the testing in which the basic functionality, operations and actions of the application/software on the basis of requirements provided is done.
  • Functional testing does the functional verification of application process in which the requirement and corresponding written code has been verified so nature of functional testing is business requirement testing.
  • Functional testing describes what the product does
  • Manual Testing or automation tools can be used for functional testing
  • Functional testing is done based on the business requirement.
  • It tests whether the actual result is working according to the expected result.
  • For Functional testing check-list of application process and documentation is required.
  • Functional testing generally gets performed before compilation of code.
  • Business requirements are the inputs to functional testing
  • In Functional testing cost of finding defects and fixing is less, also return on investment will be high as this testing involved at an early stage.

What Is Non-Functional Testing?

 Non-functional testing is a type of software testing to test non-functional parameters such as reliability, load test, performance and accountability of the software. It is designed to test the readiness of a system as per nonfunctional parameters which are never addressed by functional testing. In other words, the parameters of non-functional testing are never tested before the functional testing.

 Non-functional testing gives detailed knowledge of product behavior and used technologies. It helps in reducing the risk of production and associated costs of the software. It sets the way for software installation, setup, and execution. The measurement and metrics used for internal research and development are collected and produced under non-functional testing.

Non-functional testing is also very important as functional testing because it plays a crucial role in customer satisfaction. An excellent example of non-functional test would be to check how many people can simultaneously login into a software.

Functional and Non-functional testing both are mandatory for newly developed software. Functional testing checks the correctness of internal functions while Non-Functional testing checks the ability to work in an external environment.

Types of Non Functional Testing 

  • Performance Testing
  • Load Testing
  • Failover Testing
  • Compatibility Testing
  • Usability Testing
  • Stress Testing
  • Maintainability Testing
  • Scalability Testing
  • Volume Testing
  • Security Testing
  • Disaster Recovery Testing
  • Compliance Testing
  • Portability Testing
  • Efficiency Testing
  • Reliability Testing
  • Baseline Testing
  • Endurance Testing
  • Documentation Testing
  • Recovery Testing
  • Internationalization Testing
  • Localization Testing

What You Need To Know Functional About Testing

  • Non-Functional testing is the testing in which the performance or usability and behavior of software/application is done under different circumstances.
  • Non-Functional testing does the behavior validation and verification process which examines the expected behavior of the application based on dynamic inputs provided to the application so nature of non-functional testing is performance testing.
  • Nonfunctional testing describes how good the product works
  • It is more feasible to test using automated tools.
  • Non- functional testing is done based on the customer expectation and Performance requirement.
  • It checks the response time, and speed of the software under specific conditions.
  • For Non-Functional testing performance test cases with different scenarios for execution has been developed.
  • Non-Functional testing is mostly performed after compilation of code.
  • Performance parameters like speed, scalability are inputs to non-functional testing.
  • Non-Functional testing cost of finding and fixing defects is high and also return on investment will be low as this process involves after the development phase.

Also Read: Difference Between Unit Testing And System Testing

Difference Between Functional And Non-Functional Testing In Tabular Form

BASIS OF COMPARISON FUNCTIONAL TESTING NON-FUNCTIONAL TESTING
Description Functional testing is the testing in which the basic functionality, operations and actions of the application/software on the basis of requirements provided is done.   Non-Functional testing is the testing in which the performance or usability and behavior of software/application is done under different circumstances.  
Objective Functional testing describes what the product does   Nonfunctional testing describes how good the product works  
Testing Manual Testing or automation tools can be used for functional testing   It is more feasible to test using automated tools.  
Basis Functional testing is done based on the business requirement.   Non- functional testing is done based on the customer expectation and Performance requirement.  
Focus It tests whether the actual result is working according to the expected result.   It checks the response time, and speed of the software under specific conditions.  
Check-list For Functional testing check-list of application process and documentation is required.   For Non-Functional testing performance test cases with different scenarios for execution has been developed.  
Process Functional testing generally gets performed before compilation of code.   Non-Functional testing is mostly performed after compilation of code.  
Inputs Business requirements are the inputs to functional testing   Performance parameters like speed, scalability are inputs to non-functional testing.  
Cost In Functional testing cost of finding defects and fixing is less, also return on investment will be high as this testing involved at an early stage.   Non-Functional testing cost of finding and fixing defects is high and also return on investment will be low as this process involves after the development phase.  

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