Unit testing is a software test in which individual units or components of a software are tested. The purpose of this test is to verify that each unit of software code works as expected. Unit testing is performed by developers during the development (coding phase) of an application. Unit tests isolate a part of the code and check its accuracy. A unit can be a single function, method, procedure, module, or object.
In SDLC, STLC, v model, unit testing is the first level of testing before integration testing. Unit testing is a white box testing technique usually performed by the developer. However, in a practical world, due to developers ‘ reluctance or unwillingness to test, quality control engineers also perform unit testing.
Why Unit Testing?
Our goal here is to verify that each unit of the software occurs as designed. Writing a Unit Test makes it easy to perform a refactor in the code. When we make changes to the code, we can easily run the Unit test and test whether it works according to the algorithm we created. Unit tests do not detect all errors, because each part is tested in isolation, and when integration is performed, it does not mean that everything will work regularly.
Why is unit testing required? Let’s explain it with a few articles.
When developers write unit tests, they want to spend less time debugging, and then gain more confidence in making changes to the code. In this way, developers can be encouraged to add new features to the software and then rearrange the code, which cannot be possible without unit testing, because the confidence to act can be an issue if they are not already familiar with what can be broken as a result.
When developers write unit tests, they focus on thinking about how their code will be used throughout the system, thus leading to a better design.
3.Better Feedback Mechanism
After all unit tests are performed, the system status can be easily measured. These tests give developers information about how to evaluate other parts of the code (for example, whether it is completed or is still in development). While changes in the Test environment can affect the codebase, the feedback mechanism helps to indicate the state of a test environment.
Once developers are running comprehensive unit tests, it is relatively easy to undertake any major reorganization and reorganization with code enabled. In this way, developers can be sure that their changes will not have a ripple effect on other modules or anywhere in the system.
Removing an error can be very laborious and expensive if it is detected late in the development phase. A well-planned series of unit tests have the ability to find basic errors (which can then potentially have a major impact on the system) during development, which reduces the cost of future maintenance and prevents time loss.
Unit Testing Tools
There are several automated unit test software available to assist with unit testing. We will provide a few examples below:
Junit: Junit is a free to use testing tool used for Java programming language. It provides assertions to identify test method. This tool test data first and then inserted in the piece of code.
NUnit: NUnit is widely used unit-testing framework use for all .net languages. It is an open source tool which allows writing scripts manually. It supports data-driven tests which can run in parallel.
JMockit: JMockit is open source Unit testing tool. It is a code coverage tool with line and path metrics. It allows mocking API with recording and verification syntax. This tool offers Line coverage, Path Coverage, and Data Coverage.
EMMA: EMMA is an open-source toolkit for analyzing and reporting code written in Java language. Emma support coverage types like method, line, basic block. It is Java-based so it is without external library dependencies and can access the source code.
PHPUnit: PHPUnit is a unit testing tool for PHP programmer. It takes small portions of code which is called units and test each of them separately. The tool also allows developers to use pre-define assertion methods to assert that a system behave in a certain manner.