Unit Testing vs Component Testing

Unit testing and component testing are two methodologies that are used in software testing and development. Unit testing is a software testing process used to verify the correct implementation of each smaller part of an application. On the other hand, component testing is a software testing process used to test the external and internal interfaces of an application.

 

Unit Testing is about testing the smallest part of a function to make sure it works properly even if that goes against the natural way we, as humans, are used to. That means writing code and checking the result against a mock response generated manually by us.

 

Component Testing is different in many ways. It still checks a small unit (of code) with manual responses (a test of a particular component can pass or fail as in unit testing) but it tests the different components which are part of that component, where the relationship between components is not yet tested at all.

 

Unit testing and component testing are two closely related test types. You use them both to test an object in isolation from the rest of the system, but they differ in scale: unit tests are designed to test a class or function in isolation of other classes and functions, whereas component tests work on the scale of larger sections of code such as a module or sub-section of functionality.

The goal behind unit testing is to be able to make changes to your code whenever you want with the confidence that you haven't broken existing functionality. Unit tests can run faster than integration tests because they usually don't need to connect with external services and data stores.

 

This article defines the difference between Unit Testing and Component Testing so you can get started with testing.

 

Unit testing is a way for developers/testers to ensure that each ‘unit’ in an application is working properly. A unit is the smallest testable part of an application.

 

Unit testing is fast catching up among software developers and testers as it helps to develop software components to be testable as well as understanding the code better.

 

In programming terminology, unit testing means checking whether individual units of source code are working as expected. This is done by writing test cases and verifying whether those test cases pass or fail. It is kind of a black-box testing method in which individual units of source code, sets of one or more computer program modules together with associated control data, usage procedures, and operating procedures, are tested to determine if they meet their design specifications. The goal of unit tests is to detect defects in logic and programming before the software is shipped to customers.

 

The main difference between unit testing vs component testing is scale. Specifically, unit testing drills down into components in isolation while component testing determines interactions between a set of components.

Here is a breakdown of unit testing:

Manual unit testing refers to the kind of testing where you write all the test code manually. Even more so, this process involves writing test cases before writing the code. I know this may sound like a good idea, but in practice, many developers don’t do it because of a lack of time. Even though there is not any tool or framework to do manual unit testing, you can write your test cases and run them manually. It's slow and hard work but can give you valuable feedback about your application.

 

However, sometimes we're constrained by time or a budget. Some might say that for the most part manual unit testing is a thing of the past, since there are tools out there to automate certain parts of this process. Although automated unit testing reduces errors it doesn't find every bug in your code.

 

Manual unit testing is no fun, but it can’t be avoided if you want to test a specific piece of code in isolation which is basically what unit testing is all about. If you don’t test enough, you could be missing important bugs—but if you test too much, time spent writing tests could become prohibitive and impede progress on the core features of your product.

Unit testing is an important part of the Quality Assurance (QA) process for achieving TDD, and a must for preventing regressions and doing it manually is a necessary step to gain confidence in one’s codebase. It is a way of verifying that each piece of code behaves correctly when isolated from its dependencies. Manual unit tests are simple, low-tech, and cost little in time and resources. Such tests may not give much confidence in the system as a whole, but they provide useful feedback and aid design.

 

Unit tests make sure that your code does everything you expect it to at a lower level. Manual unit testing can become cumbersome when your test logic grows larger and more complex and that is why many developers prefer automation instead of Manual Testing.

 

Automated Testing of code is an essential practice that is employed by some of the world’s best development teams, yet it remains opaque to the vast majority of software developers. While frameworks and tools such as JUnit can help, many engineers merely know how to run tests in a terminal or call a function from a unit test. As programs get bigger, unit tests become more useful as a means of making sure your program still works the way it’s supposed to.

 

We'll discuss strategies for scaling automated unit tests in large projects along with ideas for refactoring existing codebases with a focus on introducing good unit testing practices.