What Is Functional Testing?

Functional tests are processes designed to confirm that all of the components of a piece of code or software operate correctly. Functional testing focuses on testing the interface of the application to ensure that all user requirements for a properly working application are met.

Types of functional testing include:

• Smoke Tests
• Sanity tests
• Integration testing
• Acceptance testing
• Regression testing

When Do You Need Functional Testing?

All testing strategies should include functional testing at their core. Functional tests are critical to ensuring that a product or feature will function appropriately for users. Teams should start doing basic functional tests early in development, to ensure that each component is working correctly. Functional verification testing should continue throughout the development cycle and into production.

For example, a team who is developing an e-commerce web application should start testing each feature—adding items to cart, inputting credit card information, etc.—during development. As complete interaction flows, such as the complete checkout flow, are finished, those more complex functional tests should be included as well.

How to Run Functional Tests

Both manual tests and testing automation tools can be used to run functional tests. Manual test execution is the simplest method of doing functional testing, and allows product to be tested in the same way that a customer would use it. The primary challenge of manually executed functional QA is that it can be very time-intensive, and can pull IT resources away from other activities, including development of new features and improvement of product quality and UX.

Many companies use testing automation tools like Selenium and Watir to perform their functional and regression tests. However, testing automation suites aren’t always well suited to functional testing, as they can be brittle, flaky, or miss issues that would be easy for human testers to spot. Testing automation suites can take three to ten times longer to set up than manual tests, and they must be maintained constantly. This is especially problematic for features and products that are still in development, as testing needs tend to change frequently. An additional downside of testing automation for certain kinds of functional testing is that automation tools cannot effectively emulate the user experience, and as a result, are at risk.

Rainforest QA and Functional Testing

The Rainforest QA-as-a-Service platform provides crowdsourced functional testing on-demand. By leveraging a network of 50,000 testers, Rainforest enables QA teams to run and get results from a large amount of functional tests quickly, with minimal investment of resources when compared to manual functional testing. QA managers and developers can write functional tests once, in the Rainforest platform or from a command line, then run the tests as many times as needed, across multiple browsers. Rainforest allows multiple functional tests to be run simultaneously. Unlike automated functional tests, Rainforest tests are run by human testers, and as a result Rainforest tests are less brittle and flaky, and can provide subjective feedback in addition to deterministic feature verification.

Building a comprehensive suite of functional tests helps ensure that your product and features are of consistently high quality. Learn what key functional test cases you should include in your QA testing suite when you download our free 50 Essential Functional and Regression Test Cases Checklist.