Unit Testing: Definition, Examples, and Best Practices

A software application is a complex ecosystem of many individual components, each having its own set of codes. If any of these components fail, the application may crash or lag, which can negatively impact the user experience. 

To avoid such pitfalls, integrating unit testing into your software development lifecycle is crucial. This process lets you catch bugs early, ensuring your customers enjoy an unmatched experience.

This article will guide you through the fundamentals of unit testing, its types, and the best practices to follow. Continue reading.

What is Unit Testing?

Unit testing is a type of functional testing that involves testing the performance of individual software components. In this, developers test small pieces of code to ensure there are no errors that may disturb the overall system efficiency. 

Typically, unit testing comes under the white box testing category and is performed at the start of the software development cycle, right before integration testing. As it happens early on, unit testing is carried out by developers themselves instead of a testing team. 

Why is Unit Testing Important?

Unit testing is essential for your software development life cycle as it helps you detect bugs early and also paves the way for test-driven development. Unit testing is crucial to the software testing process for multiple reasons:

Early Issue Identification

Imagine providing your customers with a software solution full of bugs, which would negatively impact user experience and your business’s reputation. It sounds like a nightmare, doesn’t it? 

Fortunately, unit testing resolves this issue by detecting bugs early in the development cycle. Developers can quickly fix these issues before moving on to the next phase, improving overall efficiency and ensuring a smoother development process.

Cost Efficiency

As mentioned earlier, unit testing is crucial in identifying issues early in the software development lifecycle. By catching and fixing these problems right away, you can reduce maintenance costs and avoid expensive last-minute fixes. Additionally, unit testing saves time for your development team, allowing them to focus on innovation rather than constant bug fixing.

Accelerated Release Cycles

To stand out in the highly competitive business world, software solutions must be released frequently. This ensures that each new feature is thoroughly tested, guaranteeing code stability and reducing the risk of bugs. Hence, developers can push updates more often or roll out new features every now and then to cater to changing customer needs. 

Test-Driven Development

Unit testing lays the groundwork for Test-Driven Development (TDD), where developers write unit tests before writing the actual code. This approach ensures that the code meets the defined requirements from the outset, resulting in cleaner, more reliable code.

Facilitates Easier Code Refactoring

Software developers often refactor code to improve its structure and maintainability. However, if not handled carefully, refactoring can introduce new bugs. 

The unit test framework is a great help in this regard. It meticulously checks each component of the software after a code change. This alerts developers to any issues, enabling them to fix problems quickly while improving overall code quality. 

Reduced Development Uncertainty

Unit testing involves checking each component of a system against a set of requirements to ensure there are no hidden bugs. This process reduces uncertainty in the development process, and developers feel confident that their code meets the necessary standards and will perform as expected in a live environment.

System Behavior Documentation

Unit testing also serves as a form of documentation for how the system behaves. Each test case demonstrates the expected behavior of a specific component, providing valuable insights for developers who need to understand or modify the code later on. It helps maintain software over time and makes it easy for new team members to revisit the code to learn about a component’s functionality. 

Reinforces Security

Another benefit of unit testing is that it helps ensure the end product is secure. How? Unit tests make it easy for developers to determine whether the designed functionalities work as intended and are secure. 

If there are any security vulnerabilities, such as potential points for SQL injections or cross-site scripting (XSS) attacks, they can be identified and addressed immediately. 

This prevents any data breaches and protects both the application and end users from potential threats. When customer data is protected, they trust your services and come for more, leading to high revenue and better business positioning. 

What is the Difference Between Unit Testing and Other Types of Testing?

Unit testing is a part of functional testing. However, functional testing only focuses on validating the functionality of an individual software component, while unit testing covers testing the functionality of a whole system. Unit testing is typically conducted at the code level; conversely, functional testing is performed at an application or server level. 

In addition, unit testing differs from integration testing. Unit testing solely relies on verifying how a single component behaves. In contrast, integration testing mainly verifies the communication and interaction between two software modules, ensuring no issues that may stop smooth data exchange. 

Integration testing has a wider scope and a higher level of complexity compared to unit testing, which is pretty easy to execute. However, when it comes to the speed and efficiency of the testing process, unit testing takes the lead, as testing a single component is easier than testing different modules. 

How Does Unit Testing Work?

Unit testing isn’t a one-step process; instead, it involves different things, from setting goals to creating and executing test cases. Let’s discuss how to perform unit testing in detail.

• Planning and Setting Up the Right Environment for Testing

First things first – you should start by designing and setting up the right testing environment. This involves picking the best testing tools and determining which part of the code needs to be tested. In addition, you must ensure that the testing environment is as similar to the production environment as possible. For instance, if you are testing a web application, you might simulate different browsers or devices to achieve consistent and authentic results.

• Write Test Cases

Next, you should develop test cases or scripts for unit testing. Typically, a test case is a specific scenario under which a code is tested to make sure it works as expected. For example, if you are testing a function that calculates the total price of items in the shopping cart, you would write test cases to check if the function correctly handles different scenarios. These may include empty carts and carts with only one or multiple items. Don’t forget to enter an expected outcome for each test to ensure accuracy.

• Execute Tests

 Once you are all done with writing test cases, the next step is to execute them. Continuing with the above example, this may involve adding items to the cart and checking if the calculator shows precise amounts and items.

• Analyze the Results

 Now, it’s time to analyze the results! Review the outcomes of each step and check if they match the expected results. If a test fails, you need to diagnose the issue, whether it’s a bug in the code or a problem in the test case. Work with the developer team to eliminate this issue and employ the unit for testing again.

Manual vs. Automated Unit Testing

As the name suggests, developers themselves perform manual testing, from test case writing to execution. However, it’s quite time-consuming and prone to errors, which may cost your business many bucks on bug fixes. Manual testing is a good supplement to Quality Assurance. On the other hand, automated unit testing involves the usage of advanced tools like diffBlue, GitHub Copilot, and Tabnine that automate the whole unit testing process and require little to no manual intervention. These tests act as the safety net for developers enabling them to easily refactor a code with confidence. They stay rest assured that even if they break something in the code during refactoring, the automated tools will detect it quickly, leading to high-quality software. 

Unit Testing Techniques

There are a few unit testing techniques that you must know about, including Structural testing and Functional testing. Let’s discuss them:

• Structural Unit Testing: One of the most common unit testing techniques is structural unit testing, in which you test the internal structure or design of the code for a specific software. In this, the development team collaborates closely with the testing team to execute software internal design. 
• Functional Unit Testing: This unit testing technique focuses on verifying the functionality of a single unit or code of software. The goal is to ensure that the unit performs as intended under different conditions. 

Unit Testing Examples

Some common unit testing examples involve Angular unit testing, Node JS testing, and Android unit testing. Here is a detailed explanation of each point:

Angular Unit Testing

Angular testing is the testing of angular applications to make sure they work in the desired manner. These angular applications are open-source Javascript frameworks that enforce a clear and organized code structure. You must carry out Angular unit tests to detect regressions in applications and to maintain overall code quality. 

Node JS Testing

Node JS Testing refers to verifying components of Node JS applications using various automated tools or frameworks. It aims to identify bugs early in the development cycle, ensure code correctness, and maintain high-quality application standards. 

Android Unit Testing 

As pretty much evident by the name, android unit testing refers to the writing and executing test cases for Android applications. In this, individual units of an Android application that may be a method or function are tested to make sure users feel satisfied with the end product. 

Unit Testing Best Practices

There are several unit testing best practices that you must follow to ensure that your testing results are accurate and reliable. These include naming the tests appropriately, following the AAA pattern, and avoiding complex logic. Let’s discuss these in detail:

Naming

The test case you write for unit tests should have a clear and descriptive name that indicates its purpose or expected behavior. For instance, if you are testing a function that calculates the total price of items in a shopping cart, a good name for the test could be CalculateTotalPrice_WithMultipleItems_ReturnsCorrectSum. This name clearly communicates what the test is doing and what results you should expect. 

Use AAA Pattern

Writing unit tests using the AAA (Arrange-Act-Assert) pattern is one of the most important practices to follow. This pattern makes the tests more readable and provides a clear distinction between the test setup, the action being tested, and the verification of the results. Here’s an overview:

• Arrange – create and set up all necessary tests and data that are required for unit tests.
• Act – you employ the method or function under test and test how it performs under certain testing conditions.
• Assert – compare the actual and expected results using assertions. If they are equal, the result is passed; otherwise, it fails.

Test Only One Scenario Per Test

Manually testing each unit for different scenarios can be really challenging and time-consuming. Therefore, the best approach is to test one scenario per test case. For instance, you should run a single test to verify if a function correctly handles valid inputs and another test to ensure it manages invalid inputs appropriately. This not only saves time but also helps you identify bugs accurately and removes any uncertainty in the code or software.

Conclusion 

Unit testing may seem like a small step in the software testing lifecycle, but it is crucial and can make or break your software quality. Therefore, it’s essential to hire an expert team of developers to perform this testing to have a top-notch software solution. Hicron Software House is a great solution in this regard. We take pride in our highly skilled team of software developers who employ unit tests after each code change or modification to guarantee that the end product meets and exceeds customer expectations. Get in touch with us today and let us take care of all your software testing tasks for enhanced reliability.