Component Testing vs Unit Testing: Top Differences, Types, and Examples

Component Testing vs Unit Testing: Top Differences & Examples

Testing is a crucial part of every Software Development Lifecycle (SDLC). It takes center stage in CI/CD pipeline, allowing developers to release reliable, resilient, and safe software. Multiple testing types exist, such as End-to-End testing, Unit testing, Integration testing, Dynamic testing, and more. And among all these different types, two important ones, Component and Unit testing, emerge in the initial phase of SDLC. As they are closely related, developers need to understand their differences. This article will specifically focus on Component testing vs Unit testing to help you understand everything about these two tests.

Difference between Component and Unit Testing

Component testing: It involves analyzing multiple functions and code modules before they form software. It is a black box testing technique that evaluates the application without considering the code information.

Unit testing: Developers perform Unit testing to ensure all the smaller code units function correctly. Unit testing is known as test-driven development (TDD) in software development. The test cases are written first; then, the bare minimum code is written to pass the test cases, followed by the final code. Unit testing is the first stage of testing for any software before it moves onto for further QA analysis.

Component Testing vs Unit Testing: Key Differences

While Component testing and Unit testing are done in the different stages of SDLC, they are closely related, but technically both are different. Here’s a table for you to easily understand Component testing vs Unit testing:

Component TestingUnit Testing
Involves testing each part or component of the application separatelyConsists of testing individual code units or modules
Developers and QA perform Component testingDevelopers perform Unit testing
Black box testingWhite box testing
Comes after Unit testing in SDLCFirst testing stage in SDLC
Validates test requirementsValidates design requirements
Does not serve as a reference document for future useServes as a good project documentation
Tester does is unaware of underlying code structureTester is aware of the underlying code
Difficult to detect issuesEasy to identify and catch defects


Although Unit testing and Component testing are closely related, they function differently and have differing purposes. The development team performs Unit testing in the initial phases of SDLC, ensuring the individual code units are working as per the requirement. On the other hand, Component testing comes right after Unit testing, which analyzes individual components for their functionality.

Both these test types focus mainly on evaluating the building blocks of an application very early in the development stage. Often, developers perform Unit and Component testing, but the task might fall on the QA team occasionally.

Lastly, there are several testing automation tools available that support Component as well as Unit testing. For instance, you can use Selenium to run test cases for your login and signup page for the example shown for Component testing. Similarly, to verify code units, you can rely either on your own Unit testing program or use tools like JUnit, NUnit, and Testsigma.

Frequently Asked Questions

Is component testing black box testing?

Yes, component testing is black box testing because the tester doesn’t know the components’ internal code logic and implementation. They perform by observing the behavior of software components in various use cases by providing different sets of input.

How is unit testing performed?

In unit testing, developers test smaller code units of the software to determine their working. A unit can be functions, methods, or classes in software. Unit testing is the first testing process in SDLC.

Is component testing the same as functional testing?

No, component testing isn’t the same as functional testing. The software applications are extensive, and it is challenging to test the entire system. For the same reason, it may lead to many gaps in the test coverage. So, before we move into integration testing/functional testing, we must finish component testing.

Why is unit testing done?

Unit testing ensures that all the smaller software units work correctly. It catches the bugs early in the software development lifecycle and helps developers save time and money. A well-written Unit test also works as project documentation and helps to migrate the code base and test cases in newer projects.

Test automation made easy

Start your smart continuous testing journey today with Testsigma.



Test Process Improvement What, When, How & Best Practices
Test Process Improvement | What, When, How & Best Practices
Test Data Definition, Types, Challenges, and Best Practices
Test Data: Definition, Types, Challenges, and Best Practices
Test Case Vs Use Case What's the Difference
Test Case Vs Use Case | What’s the Difference?