Mobile App

What is Unit Testing? What are the principles of unit testing?


Unit testing is an indispensable device in the toolbox of any serious software developer. Yet, it can sometimes be pretty challenging to write a good unit test for a critical piece of code. Having trouble testing their own or someone else’s code, developers usually think that their efforts are caused by a shortage of some basic testing experience or secret unit testing methods.

In this principles of unit testing blog, I plan to prove that unit tests are quite easy; the real difficulties that involve unit testing principles, and include expensive complexity, are a consequence of inadequately designed and untestable code. Through this blog, we will explain what makes code extremely difficult to test, which anti-patterns and poor uses we should avoid to increase its testability, and what other advantages we can accomplish by writing testable code. We will see that writing unit tests and creating testable code is not associated just with making testing less difficult. Moreover, it is about making the code itself extra robust, and more natural to manage.

What is Unit Testing?

Typically, a unit test is a program that instantiates a small division of our application and evaluates its behavior separately and it comprises basically of 3 phases: Firstly, it initializes a small portion of an application, and that portions is what we test (also recognized as the system under test, or SUT), then it uses some motive to the system succeeding the test (usually by calling a method on it), and finally, it observes the resulting performance. If the identified function is harmonious with the expectations, the unit test scores, otherwise, it fails, meaning that there is a difficulty someplace in the system under test. These three unit test conditions are also identified as Arrange, Act, and Assert, or just AAA.

A unit test can check various behavioral characters of the system under test, but most possibly it will fall into one of the two categories: state-based or interaction-based. Verifying that the system under analysis provides accurate outcomes, or that its resulting state is true, is described state-based unit testing while proving that it accurately invokes several methods are named interaction-based unit testing.

As a comparison for proper software unit testing, imagine a frantic scientist who needs to build some mythical chimera, with frog legs, octopus arms, bird feathers, and a dog’s head. (This metaphor is moderately close to what programmers actually do at practice). How would that scientist make certain that every part (or unit) he picked actually practices? Well, he can take, let’s say, a free frog’s leg, apply an electrical incentive to it, and review for proper muscle compression. What he is carrying out is actually the previously explained Arrange-Act-Assert steps of the unit test but here we have a difference and that is, in this case, the unit belongs to a physical object, not to an ideal object we make our programs from.

Principles of Unit Testing

Now let’s soon discuss the characteristics of a good unit test. Fascinating of unit testing principles that request that a good test is written below:

Simple to write

Developers typically approach a number of unit tests to satisfy multiple cases and pieces of the application’s performance, so it should be apparent to code all of the test routines without huge effort.


The purpose of a unit test should be transparent. A good unit test depicts a story about some behavioral characteristics of our application. So it should be mere to know which circumstance is being tested and if the test fails it is easy to discover how to address the problem. With a conventional unit test, we can make a bug without truly debugging the code!


Unit tests should fail particularly if there’s a bug in the system below the test. That appears pretty simple, but programmers often fall into an issue when their tests break even when no bugs were interjected. For instance, tests may qualify when departing one-by-one, but fail when operating the whole test suite, or pass on our community machine and displease on the constant integration server. These conditions are characteristic of a design imperfection. Good unit tests should be reproducible and autonomous from outside factors such as the background or running order.


Developers address unit tests so they can regularly run them and check that no flaws have been added. If unit tests are delayed, developers are more inclined to hop on running them on their own machines. One slow test won’t make a meaningful difference; add one thousand more and we’re definitely held waiting for a while. Slower unit tests can result in causing it to be dependent on the environment.

Truly unit, not assimilation. As we already revealed, unit and integration tests have various purposes. Both the unit test and the system under test should not reach out to the network resources, databases, file system, etc., to exclude the influence of external factors. That’s it — there are no mysteries to writing unit tests. Nevertheless, some techniques allow us to formulate testable code.

In a nutshell

A unit test typically highlights three different states: Arrange, Act, and Assert (sometimes referred to as AAA). For a unit test to be prosperous, the resulting performance in all three phases must be in line with expectations. If you appreciate the unit testing principles with iROID Technologies, our testers can be a great addition to your testing environment. They concede you to create unit tests in any IDE, make application models for a webpage, desktop, or applications as per your business requirements. Consult our mobile app development company in India for more details.