Things You Should Know About Functional Testing

What Is Functional Testing?

The easiest way to think of functional testing is to ask the question “does it work?” It’s a broad type of testing aimed to determine whether a product performs a specified set of business functions.

To test software features, QA specialists compare each of them to the corresponding requirement to ensure whether an output is consistent with an end-user’s expectations. This could be, for instance, receiving a confirmation email when a new user signs up to a service.

Functional testing checks:

• Do the features work as intended?
• Can an end-user interact with everything they need to?
• What happens when errors occur?
• Are there appropriate messages and a way to log these errors?

If your web or mobile app can’t perform its core tasks, no amount of good design or speed will keep consumers satisfied. So, at the end of functional testing, you should have software that has a coherent user interface, a consistent API, and seamlessly integrates with business processes.

Functional vs Non-functional Testing

Traditionally, functional testing goes before non-functional testing. But what’s the difference between these two?

Functional testing focuses on product features while non-functional focuses on user expectations. The latter measures product behavior and characteristics such as reliability, accessibility, and performance. An example of a non-functional requirement is ensuring that any update to a database is visible to all users within three seconds.

To make it more clear, let’s take a login function as an example. To perform functional testing, QA engineers would write test cases to verify that users can(not) log in when they enter the (in)correct data. These tests help determine if the function satisfies the user’s requirement.

To run non-functional testing, QA specialists would execute performance tests to determine if the system as a whole meets user expectations. Both testing types are essential. And by performing both, you will have more test coverage and a higher product’s quality.

Positive vs Negative Test Cases

The primary characteristic of a functional test is a check of a business requirement or scenario. It ensures that an app or website follows a set of business logic specifications. This, in turn, is achieved through positive and negative test cases. To get an idea, let’s look at the login feature one more time.

Let’s suppose, an app has basic safety requirements to a password: at least six characters, at least one capital, and at least one number.

• Positive test: A positive functional test will determine whether it successfully takes the above input. We create a password such as “Pa55word”. If it accepts this input, it has passed the positive test.
• Negative test: A negative functional test will evaluate what happens if the input supplied does not match specifications. In other words, how does the application handle unexpected data? If you create a password “12345678”, does it fail to register a new user? If so, that should pass the negative test, which checks if a system fails to do what it should fail to do.

Why Are These Tests Crucial for Your Product?

In software testing, functional tests deliver huge benefits to the development process. Since software development is a costly and time-consuming process, the decision of “what”, “how” and “how much” to test is highly important.

We can’t create a perfect system without bugs. However, we can make sure we’ve done everything to prevent those bugs. To achieve that, it is necessary to conduct functional testing — both positive and negative.

Benefits of Functional Testing for Business

QA specialists run functional testing to share feedback on product quality and share recommendations on its improvement if needed. So, the advantages you get as a product owner are multifaceted.

• Customer satisfaction. QA engineers estimate a digital product from an end-user perspective. So, when a system meets or exceeds user expectations, you drive clients’ satisfaction.
• Testing efficiency. A software tester can easily judge if the system passes or fails when requirements are well defined, which results in quicker and more accurate results. On the other hand, a QA specialist can share recommendations on how to create or arrange project documentation.
• No critical bugs in production. Functional testing gives you an opportunity to find and fix bugs before the release. Also, it decreases the chances of any kind of risk in the product.

Examples of Functional Bugs

Personal experience can say way more than just words. And probably, you’ve encountered some of those *annoying* bugs more than once. Occasionally, we do a small research of user reviews on different stores and platforms. They are one of the sources to get insights on what disturbs users and what would be great to fix or improve.

In a review of an e-learning platform, we found the following review, “The app won’t sync with their website and remember where you left off on a video. It won’t even remember where you left off on a video within the app if you accidentally close it.” The same app gave a headache for one of our teammates, who tried to go through a course during a lunch break, but the content won’t display on a mobile app.

When looking through the comments about fitness apps, we’ve noticed that different kinds of calculations are malfunctioning the most often. Thus, it is impossible to track calories, workout time or other essential points, which makes an app close to useless.

Some of the defects are not industry-specific, but equally critical for all the platforms. Problems with payment gateway belong here. For example, a user reports buying an online course without getting further access to it. The funds were withdrawn from the card, the access link was received, but the course wasn’t available. Such bugs can occur with any gated content, and they can be damaging for a provider’s reputation.

These are just a few examples of functional bugs, but they can give you a good understanding of what can pop up in production without pre-release testing. And though it would be inaccurate to predict a number of potentially lost users or something like that, the causal relationship is pretty much obvious.

When to Start Functional Testing

QA specialists recommend catching bugs with functions on your app or website as early in the software development lifecycle as possible. The main goal for that is to prevent defects from having a real impact on your product. Moreover, early functional testing is a cost-effective solution compared to post-release fixes.

For example, if the checkout function of your shopping app has some bugs, you can see a direct effect on revenue. Equally, if the “sign up” functionality on your website isn’t working correctly, you will inevitably suffer a loss of clients. Running functional tests early dramatically reduces the chance of this happening.

To Sum Up

Without functional testing, you can’t be completely sure that your product meets the requirements. Consistently testing product functionality ensures that customers are able to use the product as intended. It verifies product features work according to predetermined requirements, identifying areas where performance doesn’t meet expected results.