Understanding the Differences Between Functional Testing and Unit Testing

Pcloudy
5 min readMar 9, 2023

Functional testing and unit testing are essential testing approaches in application development. In this blog post, we will provide an in-depth analysis of differences between the two types of testing, when to use each type, and the types of errors they identify. We’ll also look at how achieving a balance between the two testing approaches will result in the delivery of a high-quality product.

Functional Testing

Functional testing is a crucial testing methodology that concentrates on an application’s essential features to verify that it operates in accordance with business requirements. Prior to creating functional test cases, a thorough comprehension of the application’s operational needs is required.

Functional testing assesses an application’s page transitions, user interface, data storage, screen-switching capabilities, and overall performance, focusing on the user’s viewpoint. It ensures the application’s accessibility, usability, and overall user experience, making sure that the application meets the desired expectations of its intended users.

Developing Functional Test Cases

To conduct effective functional testing, a QA professional must thoroughly review the business requirements document, familiarize themselves with the application, and design a test strategy for the specific functionality that will be evaluated. They should also select the best tool for the functional testing required and compare actual results with expected results to determine the test’s success.

Unit testing

Unit testing allows for the individual testing of an application’s various components. Each component, including elements like text boxes, buttons, and text displays, undergoes scrutiny to ensure it performs as intended. The term “unit testing” derives from the practice of viewing these components as distinct “units”. Even the smallest app component undergoes this testing process.

During unit testing, each component is assessed separately to identify any potential issues. However, components that interface with external entities, such as external databases, networks, or files, are not subject to unit testing. Developers begin running unit tests from the early stages of development to catch any issues before they can progress.

Developing Unit Test Cases

Unit testing involves evaluating every part of an application through dedicated test cases. Each test case corresponds to a specific button press or text box entry, ensuring that the functionality of all elements in a page is thoroughly tested. Multiple unit test cases are created for each page of the application, to guarantee that no element is missed.

As there are several unit testing frameworks available, it’s essential to select the most suitable one for the developer’s programming language. By leveraging the right framework, developers can ensure that their unit tests are effective and reliable.

Functional Test vs. Unit Test Comparison

Functional Testing

Unit Testing

It evaluates the usability, accessibility, and flow of the application.

Evaluates the operation of each component separately.

Includes a variety of testing methods, including unit testing and system testing.

It’s a subset of functional testing

Takes longer and examines an application’s entire usability.

It is relatively shorter and more efficient as it concentrates on specific components.

Find generic problems without being specific.

It reveals specific problems.

Aims to verify the software’s functionality, dependability, and accuracy to ensure it satisfies end user needs.

Aims to ensure the functionality of individual units or components of an application to find defects early in the development process and enhance code quality.

Let’s say we have a mobile app that allows users to book a ride-sharing service. To test the app’s functionality, we might conduct tests to make sure that users can complete the following tasks:

Create an account Login to the app Search for ride-sharing options Choose a ride and set the pickup and drop-off locations Review the estimated price and time of arrival Confirm the booking Track the ride and receive real-time updates Rate the ride and provide feedback

These tests would mimic real-world interactions and scenarios with the application, and ensure that the app is working as intended.

Unit testing, on the other hand, would focus on individual components of the app. For example, we might test the following functions:

User authentication: Can users create an account and log in? Are passwords encrypted and securely stored? Search functionality: Does the app return accurate search results based on user input? Are there any performance issues when searching for rides? Booking process: Are users able to select a ride and confirm the booking? Is the estimated price and time of arrival displayed correctly? Ride tracking: Does the app provide real-time updates on the ride’s location and ETA? Are there any issues with the map or GPS functionality? These tests would help identify any bugs or issues in specific components of the app, and ensure that each unit is working as intended.

By conducting both functional and unit tests, we can ensure that the mobile app is functioning correctly and providing a positive user experience.

For general functional testing, functional testing frameworks are employed.

Frameworks for unit testing are combined

What Do Functional Testing and Unit Testing Aim to Achieve?

Functional Testing

Functional testing aims to verify the applications dependability, accuracy, and overall functionality to ensure that it meets the end-users’ needs. It involves performing a series of tests that replicate real-world scenarios and interactions with the application to compare the results with the expected outcomes. The primary goal of functional testing is to ensure that the application operates as intended and that all components are interoperable. Functional testing is vital in identifying any issues that could negatively impact the user experience.

Unit Testing

Unit testing is used to identify and fix defects early in the development process. The primary objective of unit testing is to improve code quality and prevent regression issues. By testing each component of the application separately, it becomes easier to identify the root cause of problems and resolve them quickly. Additionally, unit tests serve as documentation, clearly outlining how the system is intended

Conclusion

It is important for testers and developers to understand the difference between unit testing and functional testing. While both testing methods are critical, they serve different purposes and should not be used interchangeably. Functional testing is more extensive and time-consuming, but it verifies that the system operates according to the business requirements.

To deliver a high-quality product, it is crucial to strike the right balance between unit testing and functional testing, ensuring that both testing methods are appropriately executed.

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