What is Unit Testing? Techniques, Examples & Types of Unit Testing

So, do you want to know about unit testing?

Okay, let’s clarify one thing: unit testing is not for everyone.

It’s a bold way of writing code.

Unit testing is a kind of automated testing in which you run a single code, check the results, and ensure the results are what you expect. Generally, unit testing is performed before integration tests; that’s why it is known to be the first level of software testing life cycle (STLC).

The main objective of unit testing is to make sure that the smallest component (Unit) of the software is capable of producing desirable input and output. These units are combined to form the system.

Unit testing is one of the popular testing techniques performed by the tester. Each unit is evaluated before combining to make a system; these units are validated based on particular requirements. Then test these units in isolation, and if any error occurs, it will be fixed.

This practice makes sure that the code offers the desired functionality and is maintainable and readable.

What is Unit Testing?

Unit testing is the most popular software testing technique, including the initial testing phase, where the minor components or units are tested individually. With this testing method, both testers and developers can isolate each module and identify and fix the system errors at the early stage of the software development lifecycle (SDLC). Unit testing is also known as the white box testing technique.

A unit testing technique in software testing is typically divided into three parts:

Initialization phase– it initializes a small piece of an application it wants to test.

Addition phase– adds a stimulus to the system under test.

Result phase– observes the resulting application behavior.

The unit test passes if the observed behavior is consistent with expectations. Otherwise, it fails. This indicates there is a problem in the system under test. These three test stages are Arrange, Act, and Assert, commonly known as AAA.

How does unit testing work?

Though the software developers or their peers generally perform the unit testing process, a team of testers can also execute it in some rare cases. Whether performed manually or by using automated tools, it follows a set procedure, which usually consists of the following steps:

Explaining and creating Unit Test Plans.
Unit test cases are designed and developed based on the defined test plans.
Execute these test cases on individual units.
Fix the defects and re-evaluate the unit.
The testing cycle continues until the unit gets rid of all the defects.

Types of unit testing

There are mainly three types of unit testing, which can help the testers to test each source code unit in isolation. Each type of unit testing fulfills the different needs of the software and ensures its proper functioning. The three types of unit testing are:

Black Box Testing: Black box unit testing allows the team to test its user interface and input and output.
White Box Testing: It is another essential type of unit testing used by developers to test the functional behavior of the product and verify its execution.
Gray Box Testing: Gray box testing is used to execute test suites and test cases, perform risk assessments, and test several methods.

Unit testing techniques

There are mainly three types of unit testing techniques, which are:

Structural technique

By using the knowledge of the software system’s structure, Structural techniques create test cases. The testers who performed this type of testing have a deep understanding of code for test case execution; therefore, the developers perform it by using the following methods:

Branch Testing
Statement Testing
Condition Testing
Expression Testing

Functional testing technique

As the name suggests, the Functional Testing technique is performed to validate the software product’s functionality and make sure it behaves in an intended manner. It is a black-box testing technique that involves:

Boundary value
Input domain testing
Equivalence Partitioning
Syntax Checking

Error-Based techniques

The individual who designed a code can make the best track errors. For this, error-based techniques are used, which allow the team to identify defects, bugs, and other discrepancies in the software. It involves:

Mutation Testing
Fault Seeding

Advantages of unit testing

Unit testing provides various benefits, including finding software errors early, facilitating change, simplifying integration, providing documentation, and many others, which we will look at in more detail.

Makes the Process Agile

You may need to change the old design and code of the software by adding more features. However, evolving already-tested code is both risky and costly. If we have unit tests in place, we can proceed with refactoring confidently.

Unit testing goes hand-in-hand with agile programming of all flavors because it builds in tests to quickly make changes.

Quality of Code

Unit testing identifies every defect before code is sent to further stages, so it improves code quality. Writing tests before coding can reveal the edge cases, and you can write better code.

Finds Bugs Early

Since unit testing is performed by developers who have in-depth knowledge of coding, bugs can be found and fixed in an early stage without impacting other code.

Provides Documentation

Unit testing provides documentation of the system. Developers looking to learn what functionality a unit offers and how to use it can look at the unit tests to understand the unit’s interface (API).

Disadvantages of Unit Testing

While there are numerous benefits of unit testing, there are some drawbacks too.

With UT, Usually, you have to write one or more test cases depending on how complicated the codes are. While the test code is pretty simple, this testing method is still more work and code, which means more hours and more cost.

Unit tests are problematic when testing your user interface. They are suitable when you need to test business logic implementation but not great for UI.

Some people believe that unit tests are problematic for a structural design. Unit tests solidify the code structure, which means changes are challenging to make.

Changing and adding new code can cause navigational issues and take more time before integration testing is even started.

Unit testing is unable to find all errors in a program.

Final Thoughts

Unit testing is needed when every unit tests separately. It is much easier to find and fix bugs at an early stage and saves a lot of time and money instead of finding them later in software development.

To make sure optimum performance of the software, unit testing needs to be implemented correctly. It is challenging to find a reliable testing provider who can handle the testing phase of your project.

Invedus Outsourcing specializes in testing software across all major industries. We have qualified virtual employees with many years of experience who can guide you through the entire procedure.

Frequently Asked Questions

What is a unit test in Agile?

A unit test, as defined by Agile teams, is a short programme fragment produced and maintained by the product team’s developers that exercises a specific section of the product’s source code and verifies the results.

Why is unit testing done?

The primary goal of unit testing is to determine written code and test it to see if it works as intended. Unit testing is an important phase in the development process because, when done properly, it can assist uncover early faults in code which might be more difficult to find later in the testing process.

What do you mean by unit testing?

Unit testing is a software testing process that examines the smallest testable components of an application, known as units, individually and independently for appropriate operation.

What techniques are used in unit testing?

There are three forms of unit testing that can assist a unit testing team in testing each unit of source code in isolation. Each of these forms of unit testing caters to distinct programme requirements and ensures appropriate operation. The following are the various types of unit testing:

Black Box Testing
White Box Testing
Gray Box Testing

What is the difference between the types of unit testing and functional testing?

Unit Testing vs Functional Testing can be defined as- Unit testing assists in isolating individual code and determining whether the unit performs as intended. The purpose is to enable early discovery of code problems that might be difficult to identify and fix during later phases of testing. Functional testing ensures that each app feature functions as intended.