What is Functional Testing? Types and Examples

Functional Testing: What Is It?

In functional testing, testers examine if the features of the system under test are operating in accordance with the requirements and functioning as intended. The stakeholders (development team or product owner) or the users themselves supply these requirements. For this reason, functional testing is sometimes referred to as specification testing.

Functional testing often doesn't focus on the underlying code structure or implementation specifics, instead ensuring that the software fulfils its assigned tasks.

One of the most popular and fundamental kinds of testing is functional testing. Functional testing is frequently in mind when people use the word "testing" in a general sense.

Functional Testing Examples: 1. Functional Testing for the Login Function

Let's say you are testing an online application that needs users to register. Here, functional testing is merely performed to verify that the login page functions as intended.

So what things can one "expect" from a login page? A few that sprang to mind are:

User Authentication

Account Lockout

Password Reset

Remember Me

Account Recovery

Multi-Factor Authentication (especially critical for high-risk applications)

Session Management (ensure that users are logged out automatically after a period of inactivity for security purposes)

1. User Monitoring

In order to direct the functional testing endeavour, those requirements have been decided upon and thoroughly documented. Functional testing for the Login feature usually needs to be done more when security is prioritised. The following are a few instances of useful test cases found on the login page:

Verify if users are able to log in successfully using their correct login information, such as a registered username or email and password.

Verify that users who attempt to log in with improper credentials—such as an erroneous password or a nonexistent username—receive an error message.

Verify that the user's account gets locked and they are unable to log in after a predetermined amount of unsuccessful tries to log in.

By submitting a password reset request using the "Forgot Password" link, you can test the password reset functionality.

To make sure the user stays logged in during browser sessions, test the "Remember Me" option.

Verify that the MFA method (such as an SMS code or app-based token) is operational and test the MFA implementation by signing in with legitimate credentials.

1. E-commerce Website Functional Testing

Comparably, in order to verify the functionality of particular features like product search, shopping cart, or even the checkout process, we also require functional testing for eCommerce websites. Functional testing on those websites looks like this:

Verify that consumers may use various search phrases to find products.

Make that the appropriate products, together with their costs, descriptions, and photos, are displayed in the search results.

Make sure users can remove goods, change amounts, and empty the cart whenever necessary.

Check if you can add items from product detail pages and product listings to the shopping cart.

Test all aspects of the checkout process, including choosing a payment option, entering shipping details, and checking the order.

How Functional Testing Is Done

Requirements are the first step in functional testing.

The user story is where requirements begin.

Fundamentally, functional testing involves converting the user story into the appropriate requirements, which are subsequently transformed into the appropriate test cases.

Generally, a user story has the following structure:

As a [role]: This indicates the kind of stakeholder or user that will profit from the functionality.

I want [feature]: This expresses the particular feature or ability that the user is looking for.

Thus that [benefit]: This gives context for the desired feature's implementation and clarifies its purpose.

For example, a user story might look like this:

"As a customer, I want to be able to view my order history online so that I can track the status of my purchases."

Although this user story is good, the development and quality assurance teams need more. At best, they serve as a good beginning point. It is imperative for testers to collaborate closely with end users, sit down with them, understand the problem from their point of view, and contextualise the user story to make sure the feature is produced according to their wishes. It becomes necessary to have a user story, a realistic example, and a dialogue. The first functional tests that would eventually direct development efforts are derived from this requirement.

How then do we go about doing that? "Divide to conquer" is the crucial phrase here.

A user story could be overly broad. The user wants X, but in order to get there, what precise steps need to be taken? Divide the user story into manageable, smaller pieces. In addition to allowing you to develop and test that little portion of the tale more quickly, this technique greatly reduces the risks connected with the story.

Important Distinctions Between Non-Functional and Functional Testing

Functional testing is a crucial component of any test plan, but it shouldn't be the only kind of testing your team does. The much-needed complement to functional testing, non-functional testing effectively fills in the gaps that functional testing leaves behind.

What is testing that isn't functional?

Software testing that concentrates on assessing non-functional aspects including system performance, stability, and dependability is known as non-functional testing.

In other words, during functional testing, testers attempt to provide a response to the question Is the system able to perform its intended function? In non-functional testing, testers attempt to provide an answer to the query. Can the system perform its intended function sufficiently well?

Here are five non-functional test scenarios to help you grasp the idea:

Calculate the system's reaction time with a typical load.

In order to assess the system's performance under high load and look for breakdowns or degradation in response time, simulate multiple user connections.

To get input on navigation, intuitiveness, and the entire user experience, test usability with real users.

To evaluate the system's capacity to manage a higher workload, progressively add more work while monitoring performance indicators such as CPU and memory utilisation.

To make sure users can only access the functions and data they are authorised for, test user roles and permissions.

Functional Testing Types and Examples

Functional testing includes testing at the component level as well as regression testing on already-released features. It manifests itself in all forms of functionality testing.

1. Unit Testing

Developers use unit testing as a sort of functional testing while they write code and construct applications. Unit testing is used to verify a unit's or component's functionality by ensuring that, given a set of inputs, the intended outputs are produced. Being the most detailed test, it lays the groundwork for more intricate, extensive, and integrated features. For those looking to expand their skills in unit testing and other testing methods, exploring a comprehensive program like the best software testing course in Delhi, Noida, Mumbai and other cities across India can be beneficial.

For instance, a restaurant that wants to allow patrons to place orders at their tables without a server needs to have an app. To test the "add to order" method, the developer would write a unit test. Unit testing would also include other individual functions like "remove from order" and "submit order."

2. Module testing, or component testing

Because they both isolate and validate a specific functionality, component testing and unit testing are similar. However, stimulative interactions with sample test data, or stub and driver, may be required for component testing at this stage.

As an illustration, a healthcare service app can assist patients in making appointments with the doctors of their choosing. The part of the system that uses GPS data from the user to display "nearby" hospitals or healthcare facilities is what needs to be tested. The user's profile serves as the counterfoil and the health care provider's available schedules as the driver in order to test this function.

3. Integration Testing

Although individual modules and components may pass, quality engineers must nonetheless guarantee their collective functionality. Since modules and other system components are frequently developed independently by several developers, integration testing is essential to ensuring that the system's components function as intended.

Microservices, which are interoperable components of modern software architecture, are frequently used. Integration testing must be performed on these communications to make sure everything is working as it should.

Example: Users can create a savings account using a feature of a banking app. It has the capacity to move money from their primary account to the savings account. Since the two modules are independent, integration testing is necessary to make sure that transactions between them are seamless and accurate.

4. Sanity Testing

Sanity testing is done for a new build that includes new code or small problem fixes, much like regression testing. The build will not be subjected to additional testing if it is rejected during the sanity testing stage. While sanity testing focuses on particular sections affected by new code or bug fixes exclusively, regression testing tests the entire system following changes.

Example: Even when the product is in stock, customers cannot add it to their cart on an online store. Sanity testing is done once the problem has been resolved to make sure the "add to cart" feature is operational.

The foundation of software testing is functional testing, which guarantees that applications not only fulfil specifications but also provide a great user experience. It verifies that each and every software component functions as intended.

Functional testing requires a systematic approach in order to be done well. This covers comprehensive planning, designing, executing, and reporting test cases.