Difference Between Unit Tests and Functional Tests Last Updated : 07 Oct, 2022 Comments Improve Suggest changes Like Article Like Report The article focuses on discussing the differences between Unit Testing and Functional Testing. The following topics will be discussed here: What is Unit Testing?What is Functional Testing?Unit Testing vs Functional Testing Let's start discussing each of these topics in detail. What is Unit Testing? Unit Testing includes the testing of each unit or an individual component of the software application. The main aim behind unit testing is to ensure that each unit or individual component is working as expected. Unit Testing breaks the source code into various units and validates that every unit is working the right way. In this way, early bugs and their fixes can be detected in the development cycle. Also, it helps the developers to have a basic understanding of every unit, which also enables them to make modifications faster.What is Functional Testing? Functional Testing is the testing of the system to validate that the software system will work efficiently as per the functional requirements. The main aim of functional testing is to verify that each function works properly against the functional requirements and specifications. In functional tests, each functionality of the software application is tested by providing an appropriate test input and checking whether the output is as expected. It helps to find defects in the system that the developers might have missed during the application development, and also it provides information about the quality of the output data.Unit Testing vs Functional Testing Both Unit Tests and Functional Tests are done to identify defects, prevent them and thus, deliver a quality product. Below are the differences between Unit Testing and Functional Testing. FactorsUnit TestingFunctional TestingPurposeThe primary purpose behind the unit tests is to verify that individual modules are working properly.The primary purpose behind the functional tests is to verify that the software application is working properly.Written byUnit tests are written by the developers Functional tests are written by the testing team.Performed duringUnit tests are performed during the software development cycleFunctional tests are performed during the level of application testing.Testing TechniqueWhite Box Testing Approach is used for unit testing and is usually done by developers.Black Box Testing Approach is used for functional testing and is usually done by testers.ErrorsPerforming unit tests are helpful for detecting early bugs/problems in the codePerforming functional tests are helpful for detecting defects in the functionalityCost and maintenanceThe cost and maintenance of doing unit testing are low.The cost and maintenance of doing functional testing is high.No. of test casesThe number of test cases is higher than functional testing.The number of test cases is lower than unit testing.SpeedIt is faster than functional testing.Functional testing is slow and quite complex.ModificationsModifications are done frequently in unit testing.Low rates of modifications are needed for performing functional testing.PerspectiveUnit tests are written from the developer's perspective to ensure that every individual component is working as it is expected from the developers' code.Unit tests are written from the users' perspective to ensure that the software system is working as it is expected by the userTesting tools Some commonly used unit testing tools are - Jtest, NUnit, EMMA, and PHPUnit. Some commonly used functional testing tools are - Selenium, QTP, SoapUI, and Watir. Comment More infoAdvertise with us Next Article Difference Between Unit Tests and Functional Tests D disha55handa Follow Improve Article Tags : Difference Between Software Testing Similar Reads Difference Between Unit, Functional, Acceptance, and Integration Tests Here, we will discuss the differences between unit testing, functional testing, acceptance testing, and integration testing. Unit Testing It is a testing technique wherein the simple or smallest units of a software program are examined personally for bugs and errors. These smallest units may be exam 7 min read Difference between Unit Testing and Integration Testing Unit Testing: Unit Testing is a type of software testing where individual software components are tested. Unit Testing of the software product is carried out during the development of an application. An individual component may be either an individual function or a procedure. 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