Unit Testing: The 101 guide to everything you need to know

Unit testing is indispensable to the success of a software development lifecycle (SDLC). It helps ensure individual units of the code are working as intended.

This post will help you look closely at unit testing and how it fits into the development lifecycle. We will also discuss some benefits of unit testing and why it is the lifeblood of software development in today’s day and age.

What is Unit Testing?

Unit testing involves conducting small, autonomous tests that verify individual units of code. A unit is a minor component of an application or software, processed individually to determine if the code works as intended.

Unit tests can be run automatically and frequently to catch errors and regressions early in the software development lifecycle (SDLC), saving time and money. These tests are also used to verify coding assumptions.

As part of a test-driven development, unit testing enables a meticulous approach to software development through continuous testing and review. However, it is just one part of SDLC. Other important aspects include integration testing, system testing, and user acceptance testing. All of these together help to create a high-quality and robust final product.

Types of unit tests

Unit tests are either manual or automated.

Manual testing is performed by running the software and assessing the output or by writing test scripts executed by the software. Manual testing is often used to test small pieces of code or code that are not yet ready to be automated.

On the other hand, automatic tests rely on test frameworks to nip the bugs and defects in the bud. These frameworks are not only helpful in flagging and reporting failures but also in conducting a report of all testing cases.

The need and significance of Unit Testing in SDLC

Unit testing is the cornerstone of the testing pyramid. As part of the software development life cycle, they can be run frequently and inexpensively to detect errors before they multiply as more significant, more complex problems.

Additionally, unit tests can automatically verify that changes to the code do not break existing functionality. Developers find it easier and more efficient to make alterations in the code, knowing that their changes will not break anything else in the system.

Finally, unit tests can document how the code is supposed to work. When done well, unit tests can be read like prose and provide valuable insights into how the system works. This can be especially helpful for new developers who are joining a project or for future maintenance tasks.

Some of the benefits achieved through Unit Testing include:

1. Improved code quality: By forcing developers to think about edge cases and error handling, unit testing helps improve the overall quality of the code base. Additionally, writing comprehensive unit tests can help ensure that all aspects of the code are covered and tested.
2. Preventing regressions: Regressions are errors that occur when previously working code starts to break after new code is introduced. Unit tests can help prevent regressions by ensuring that new code does not break existing functionality.
3. Acquired documentation: Unit tests can indicate how the code is supposed to work. This can be especially helpful for other developers who need to understand or make changes to the code base.
4. Boosted confidence: By catching errors early and ensuring that tests cover all aspects of the code, unit testing can increase confidence in the stability and quality of the code base.

Who performs Unit Tests?

It is the developers who are responsible for writing unit tests in software development. When developers perform unit tests, they gain feedback on whether or not the product features are built correctly. Moreover, these tests inform if code alterations have impacted the existing functionality.

How do developers write Unit Tests?

There are many ways to write unit tests, but most developers follow a similar process.

First, they identify the functionality they want to test. This could be a specific method or function, or it could be a group of related methods. Next, they write test cases for that functionality. A test case is a set of input and expected output values.

Once the test cases are written, the developer writes code to execute those tests and compare the actual output to the expected outcome. If the two match, the test is considered successful. If not, the developer knows there is an issue with their code.

How to write good Unit Tests?

Writing good unit tests requires some practice and experience. Here are some tips:

1. Keep them small: As we mentioned before, unit tests should only test one thing at a time. If you find yourself testing multiple things in one test, it's probably too big. Try breaking it down into smaller tests.
2. Think before you write: It is imperative that developers identify various inputs they can leverage for the test case or group of test cases.
3. Make them independent: Unit tests should not depend on each other. This way, if one test fails, it doesn't affect any other tests.
4. Give them clear names: A good name for a unit test should describe what it's testing and why it is essential. For example, "test_login_successful" is a good name for a test that checks if a user can successfully log in to the system.
5. Use assert statements: Assert statements are used to check if a particular condition is true or false. If the condition is false, the assert statement will fail, and the test will stop running. Assert statements are typically used to check if the output of a certain function is what we expect it to be.

The demerits: Unit Tests are known to hamstring the speed of an SDLC.

Unit tests present a rosy picture overall, but every rose has its thorns.

Several software professionals have admitted to having reservations about unit tests. These range from unit tests being time-consuming to limitations in terms of coverage and the potential for false positives. We have highlighted some of the key disadvantages of unit testing below.

1. Time-consuming: Writing and maintaining unit tests can be time-consuming, especially for large or complex codebases.
2. Brittle tests: Unit tests can become brittle over time and break easily when the code changes, requiring updates to the tests.
3. Limited coverage: Unit tests only verify small, isolated parts of the code, potentially missing issues that arise when these parts are integrated.
4. Over-reliance: Over-reliance on unit tests can lead to a false sense of security and neglect of other testing methods.
5. Debugging: Debugging failed tests can be difficult and time-consuming, especially when the cause of failure is not immediately apparent.
6. Initial setup cost: Setting up a unit testing framework and writing initial tests can be a significant effort and may not provide immediate value.

The role of the QA team

It is a common misconception that unit tests fall under the domain of QA engineers.

Truth be told, the QA team comes into the picture only when unit tests are completed. The QA team is responsible for finding weak links that unit tests didn’t pick up. They adopt a series of procedures:

1. Smoke testing
2. Sanity testing
3. Retesting
4. Regression testing
5. Exploratory testing
6. Acceptance testing
7. Performance testing

What is Buddy Testing?

Buddy testing, also known as peer review, is a software testing technique executed by the QA and DEV teams to test a component or system. This type of testing can help improve the quality of the test cases and ensure that errors are spotted and fixed quickly. Buddy testing is typically done after unit testing is completed.

There are several benefits to using buddy testing, including:

1. Improved test coverage: When two teams work together, they can cover more ground and test more features than a battery of professionals alone. This can help to identify more bugs and potential problems with the software.
2. More thorough testing: QA and DEV teams working together can provide a more thorough test of the software than a few testers working alone. This is because each team can focus on different aspects of the software and it can share its findings.
3. Faster bug fixes: If a bug is found during buddy testing, it can be fixed immediately, as both teams are aware of the problem. This contrasts traditional testing methods, where a bug might not be discovered until after the software has been released.
4. Improved communication between developers and testers: Buddy testing can improve communication between developers and testers, as both groups work together towards a common goal. This can help to ensure that bugs are fixed more quickly and that new features are adequately tested before being released.

Kellton’s expertise in Unit Testing and the tools we use

At Kellton, our professionals are a stickler for the highest standards of quality and effectiveness of the software products. Whether our clients want to bring a new product into the market or transform an existing one fundamentally, we have the skills and capabilities to ensure systems and applications deliver a differentiated user experience. The testing teams at Kellton are well-equipped to work as a standalone unit or an extension of your team to deliver:

1. Quality-rich integrations from time to time.
2. Automated touchpoints across all application and architectural layers.
3. Maximum efficiency, speed, and cost-effectiveness.

We push the boundaries of what’s possible by leveraging cutting-edge unit testing tools, which are the following:

1. Selenium

Selenium is an open-source tool for automating tests carried out on web browsers. It allows testers to write scripts in Java, Python, C#, Ruby, PHP, and more. Selenium is a widely popular automation framework because it can be easily integrated with tools, such as TestNG and JUnit, for managing test cases and generating user reports. 

Kellton has broad expertise in implementing Selenium to automate web browser application tests. We mitigate the hassles of testing web applications by offering comprehensive Selenium-based automation testing services, which help our clients build better apps and take them to markets as quickly as possible.

2. Cypress

Cypress is an end-to-end testing framework designed to make it easy to write, run, and debug tests for web applications. Cypress runs directly in the browser and can interact with your application the same way a real user would, which allows for accurate and reliable testing. Cypress also includes features such as automatic waiting, network traffic control, and real-time reloading to make testing faster and more efficient. Developers and testers widely use cypress to automate their testing process and increase the reliability of their web applications.

Kellton provides the entire length of Cypress-based automation testing services for native, hybrid, and mobile web applications. We help our clients build qualitative, reliable applications that deliver true service value in the market of substantial digital potential.

3. Mocha

Mocha is a JavaScript testing framework that runs on Node.js and in the browser. It is a feature-rich framework that allows for asynchronous testing, test-driven development (TDD), and behavior-driven development (BDD) style of testing. Mocha tests run serially, allowing for flexible and accurate reporting while mapping uncaught exceptions to the correct test cases. It also provides a way to test both synchronous and asynchronous code with a simple and easy-to-use API, making it a popular choice for testing Node.js applications and browser-based applications built with JavaScript frameworks such as React or Angular.

Mocha is commonly used with Chai to test JavaScript applications. While Mocha provides the structure for organizing and running tests, Chai delivers a way to write assertions that check the outcome of the tested code. 

Our QA experts offer a complete set of Mocha testing services to validate the safety and reliability of the applications. We identify the potential security threats, compliance gaps, and privacy issues in our testing and implement the best optimization strategy that drives outcomes with greater agility.

Conclusion

Unit testing is integral to a software development lifecycle, ensuring a bug-free, fully functional product at the final lap. Being inexpensive, they fit in the budget easily and can be run as often as possible. Unit tests are focused on augmenting any SDLC's efficiency, effectiveness, and speed. Without unit tests, the whole process will bog down, and the testing team will be burdened with extra work. Organizations must try building awareness around the need and benefits of unit testing and get the buy-in from key people. This will be instrumental in opening better, more enhanced discussions about code quality.