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The Fundamentals of Functional Testing

Kelly Lyons

Can our users do what they need to do? Does our product actually work the way it should? What are we missing? These are just a few of the questions that keep developers up at night as they near the launch or update of a new product that they’ve been tirelessly working on for months. With functional testing, you can get answers to those questions and ensure your software is ready for market in time for launch. Read on to learn how:

What is Functional Testing?

Functional testing ensures that your software works as designed from the user’s perspective by checking your product from head to toe, conducted by someone without prior knowledge of how the code functions internally. You might think of it like checking for all of your belongings before you leave the house. You’re not making sure that your clothing was acquired legally or put away in the right drawers, but that you have a jacket, wallet, keys and your phone.

Functional testing is similar in that you’re checking every function of the application works as required before the product is released to the public. You’re not consumed by details of the internal structure like you would be in development phase. It puts you in the mindset of the user, so you can identify glitches that could harm user experience (and ultimately the success of your app).

Good functional testing not only tests that everything functions as expected to, but it also uncovers unanticipated issues. In an ideal world, you would have a list of every test case covering every behavior possible in your software, but, in the real world, there will always be gaps. With the fast pace of innovation in agile environments, it can be too easy to make assumptions from user stories about how software should work. By working with creative and empathetic crowdtesters who aren’t afraid to stray from the happy path, you can uncover unknown bugs in your software, so you can provide the best product possible to your customers.

The Elements of Functional Testing

Functional testing is a comprehensive approach to uncovering bugs. Therefore, it requires testers to check your product from top-to-bottom, including:

  • User Interface: Testers test whether a user can navigate the app without any difficulties. Anticipating what the user wants to do and planning for them to be able to do so is a valuable step in the software development process. For instance, how easy is the signup process? How easy is it to buy something? These things can all have a big impact on retention and loyalty.
  • Error conditions: This determines that error messages are displayed as needed and errors are handled gracefully. This becomes particularly important for story-driven agile teams, where stories often focus on “happy outcomes” to the exclusion of errors.
  • Text handling: This considers input, copying, pasting, and editing for text including extended characters, special fonts and non-Latin scripts.

Functional testing requires you to identify the test data, compute the expected outcomes, execute test cases, and compare actual and expected results to determine in practical terms what the product does and if it is doing so as planned.

Why Functional Testing?

Effective functional testing replicates user and business requirements for the software. The primary objective is to simulate the way the software system or application will be used. This intends to remove developer assumptions entirely from the process and identify what exactly each function is meant to do, what it will look like if it functions correctly, and determine whether it actually does that. For instance, function testing can highlight:

  • Missing functionality: when the application is not capable of doing what was expected.
  • User interface errors: when data is received but the user cannot act on it because of issues in the user interface.
  • Incorrect specifications: when specifications are incomplete, incorrect or inconsistent.
  • Errors communicating among components: when components of a system work correctly in isolation but don’t come together properly.

The functional tester is not blinded by excitement over building a new feature in the code or burdened with knowledge of how the code was built. Instead, the tester’s goal is quality assurance and making sure the software is released to users with full functionality—doing what the coders intended and doing so well.

Successful QA testers will also employ both positive and negative testing. While positive testing sets out to make sure that a software application will perform as planned, negative testing does the opposite. Negative testing is a little like trying to get the software to beg for mercy. Determining in advance what causes the software to fail lets you release more stable and reliable software. Identifying potential problems proactively also allows developers to outline in advance what actions the user cannot take and plan to handle issues in a more user-friendly way. In our next blog, we’ll discuss the types of functional testing and how crowdtesting and automation can work together to ensure your product is working as expected.



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