Audvik Labs

Learning about Unit Testing

Testing of the unit requires testing individual components of the programme or application software. The primary objective behind this is to verify that all the individual components function as expected. 

As the smallest possible part of the software that can be evaluated, a unit is known. It usually has a couple of inputs and a single output. 

Both testers and developers can isolate each module, detect and repair device defects at a very early stage of the life cycle of software development with this testing method (SDLC). 

Benefits of unit testing 

Some benefits of unit testing include: 

•Simplifies debugging: By testing the functionality of small units, you can catch bugs before they affect more units in the integrated application. 

•Encourages more loosely coupled code: By intentionally reducing interdependencies between units, we get more loosely coupled code, a coding best practice. 

•Faster than functional testing: As units are very small, you can run several unit tests in seconds (provided you’ve automated them). 

•Minimize code regression: After code is refactored or extended, you can rerun all test suites to ensure your new or updated code doesn’t break existing functionality. 

•Better code coverage: By breaking an application down into the smallest testable components, unit testing helps increase your code coverage. 

Why Unit Testing is essential? 

By considering stubs, mock artifacts, drivers, and unit testing frameworks, this methodology effectively helps validate the consistency of a section of code. 

Because it is practiced at the initial testing level, this testing methodology ensures that the vulnerabilities are detected and corrected at the early stage of SDLC, even before they become costly for businesses to repair when they are later identified. 

The developers and testers can help save time with a suitable unit testing practice as bugs can be found early in the process as it is the initial testing step. Skipping or restricting the unit testing practice will adversely increase the defects, and repairing them later becomes difficult. 

A typical unit test consists of three phases which include the first initialization phase where it initializes a small piece of an application it wants to test. The second phase is the addition phase where it adds a stimulus to the system under test and finally, the third phase is the result phase where it observes the resulting application behavior. Evidently, if the observed behavior is consistent with expectations, then the unit test passes else it fails. This indicates there is a problem somewhere in the system under test. These three test phases are named as Arrange, Act and Assert or commonly known as AAA.

Unit testing types : 

White Box Testing 

This testing practice is also known as transparent testing or glass box testing. In this unit testing type, the functional behavior of the software is tested by the developers in order to validate their execution. 

Black-box Testing 

In this unit testing type, the unit testers are not aware of the internal functionality of the system and are allowed for testing the structure of the function, i.e. the user interface, input, and output. 

Gray Box Testing 

Gray box testing is popularly known for being the combination of both black-box and white-box testing. In this method, the tester is partially aware of the system functionality and uses this approach for testing various test methods, for executing test suites, and to perform the risk assessment. Also, this unit testing type is known as semi-transparent testing. 

Top unit testing frameworks 

There are a number of testing tools developers can use for testing. Here is a list of top frameworks for unit testing: 

Mocha – a JavaScript test framework running on Node.js and in the browser. 

JUnit – a simple, open-source framework to write and run repeatable tests. 

NUnit – a unit testing framework for all .Net languages. It initially derived from JUnit, however, completely rewritten and features were expanded for .Net projects. 

xUnit – an open-source unit testing tool for .NET Frameworks, it was written by the original author of NUnit. 

TestNG – a testing framework inspired by JUnit and NUnit yet with more powerful features. 

Jasmin – a behavior-driven development (BDD) framework for testing JavaScript code. 

RSpec – a BDD testing framework for Ruby

PyUnit – a standard unit test framework for Python

PHPUnit – a programmer-oriented unit testing framework for PHP. 

Disadvantages of Unit Testing 

Some of the major disadvantages of the unit testing framework are : 

•This method focuses on a unit of code that prevents it from catching integration errors. 

•Unit testing doesn’t catch every error of the application. 


To offer a qualitative and bug-free software solution to the clients, the software development team takes the system through a proper testing process and this includes applying unit testing at the initial stage. Unit testing focuses on the code of the system and separates the small modules of the program and tests them individually. Basically, unit testing helps in testing code and fixing the bug before the rest of the software development life cycle is carried forward. This type of software testing ensures that the developed system is quality assured and bug-free. 

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