A Guide to Functional Testing

Software testing comprises different types of testing but is broadly classified into Functional testing and Non-functional testing. The former is what we are going to discuss today. We will understand what functional testing is, how it is performed, and how it is different compared to non-functional testing.

What is Functional Testing?

Functional testing is a type of testing that checks the software against the functional requirements. The purpose of functional testing is to ensure that every feature of the software application functions or provides the same output as expected. In functional testing, each function is tested by providing appropriate input and verifying the output against the functional specifications or expected output.

Functional testing is a type of black-box testing as it doesn’t involve the source code of the application. It can include sanity checks, integration testing, or system testing. It checks the User Interface, API, database, etc., and can be performed both manually and through automation.

What does Functional Testing involve?

Functional testing primarily focuses on checking-

1. Key functions of the software application

2. Usability aspects to check whether a user can easily navigate through the application

3. Error conditions to check if the system is displaying error messages when it has to

How to perform Functional Testing?

Performing Functional Testing involves five main steps-

1. Thoroughly understand the functional specifications

2. Identify test input based on requirements

3. Assess the expected outputs with selected test data values

4. Execute test cases

5. Compare the actual output with the assessed output

In Comparison to Non-Functional Testing

Just like functional testing focuses on the functional aspects of the software application, similarly, non-functional testing focuses on the non-functional aspects of the application such as performance, reliability, scalability, etc. There are a few differences between the two. For instance, non-functional testing is performed after functional testing. While the latter describes what the product does, the former helps understand how well the product works. You can also say non-functional testing focuses on the results of processing whereas functional testing focuses on the mechanics of processing.

Examples of functional testing include- Unit Testing, Smoke Testing, Regression Testing, etc.

Examples of non-functional testing include- Performance Testing, Compatibility Testing, Load Testing, etc.

Functional Testing Best Practices

Follow the below-mentioned points for effective functional testing-

1. Create Test Cases Early

You don’t need to wait for the application or the modules to be coded completely in order to create test cases. Create them early, as user requirements would be the freshest in the initial phases of the project. You can always make the changes later as needed.

2. Automate what can be

Functional testing can be an arduous and tedious affair. By automating test cases, you can perform tests and address the issues faster, thereby saving an ample amount of test time and costs. It doesn’t mean that you automate all test cases; it may not be even possible and neither is the ideal thing to do, but automating the important test cases can significantly improve your ROI. You can automate tests that need to run repeatedly, which are the same but with different data, or the ones that are prone to human error.

3. Understanding the Thought Process of Target Users

An application doesn’t cater to just one particular type of user. It can have different types of users. Therefore, its important to take into account those different users and understand how each type would navigate the application.

4. Prioritize Features

Prioritize the features that are the mainstay of your application and test them. You can’t always test each and every feature but prioritizing them helps ensure that the most important features are covered during the test.

5. Test Frequently

Prepare an automation test checklist and strategize for the execution of this checklist at regular intervals. By doing this, QAs can enhance the test automation framework to make it more robust. This practice also helps you identify more software bugs.

Benefits of Functional Testing

Conducting functional tests offers the following advantages-

1. Ensures that the product is free from any functionality errors.

2. Ensures that the product functions as per the requirements.

3. It significantly improves the quality of the software application.

4. Improves customer satisfaction.

Functional Testing Tools

Some of the tools that are used for functional testing are-

1. SoapUI

SoapUI is amongst the leading functional testing tools for SOAP and REST testing. An open-source tool having a user-friendly graphical interface and enterprise-class features, SoapUI lets you quickly create and execute automated functional, regression, and load tests.

2. Selenium

Selenium is a popular open-source tool that is used for functional testing on both web and desktop applications.

3. Watir

Web Application Testing in Ruby or Watir is an open-source tool developed using Ruby that helps automate web applications irrespective of the language they are written in. It supports multiple browsers such as Chrome, Firefox, Edge, and more.

Final Thoughts

Functional testing is an integral part of software testing that decides whether the product that you are creating or have created functions exactly like what you or your client expected. It sets the foundation for a top-notch software product and should never be overlooked at any cost. Although this can be a bit challenging for some organizations, its benefits far outweigh the challenges. Ultimately, you will be able to create a product that meets users’ requirements and enriches the user experience.