What is white box testing vs black box testing? (and when to involve a QA agency) - image of a puppy in a box
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What is white box testing vs black box testing? (and when to involve a QA agency)

Posted by Brian Borg on Apr 29 2021

'The distinction here is based on what the person knows or can understand.'

That's how Bret Pettichord differentiates white box vs black box testing, and it makes sense.

The two methods give rise to spirited debate in the software testing world. To help make sense of the difference, we're putting white and black box testing methods head-to-head. Understanding the contrast makes it easier to determine when it's best to involve some unbiased and knowledgeable third-party testers.

What is white box testing?

White box testing (also known as clear, glass or transparent box testing) takes place during the development stages. It requires testers to have familiarity of the actual software code. They use their knowledge to check the outputs of the items they are testing, and the internal variables that lead to that output. Pretty straightforward! Knowledge of the code also allows the tester to confirm that all programmatic constructs (loops, conditionals, etc) are being tested through the front end, so a thorough coverage assurance is confirmed.

What is black box testing?

Black box testing is conducted from an external or end-user perspective. The internal structure and design of the software being tested do not need to be known by the tester. This type of testing takes place to ensure the application performs how it should from a variety of actions and data possible and the user experience is smooth.

You might also hear of a combination of both methods being referred to as grey box testing.

Now that we've established the difference between the two, we can make an educated decision about involving third parties. When — and why — should you use a QA agency to perform these testing methods?

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Involving a QA agency in your white box testing

If you want to involve a QA agency in your white box testing, they need to know the internal structure and design of your software application. The nature of this methodology means that it's valuable to engage them earlier in your project.

Early engagement affords QA professionals the opportunity to build a relationship with your developers, as well as gain knowledge and experience with the software. Remember - if you decide to handle white-box testing in-house, your developers or testers should perform it during the development process.

That last point is significant. Because white box testing takes place during development and requires knowledge of the code, you won't usually need to involve anyone but an engineer from the development team. Professional, third-party testers (like us) start to come in very handy when you get to the black box testing stages later during the QA step of the development cycle.

Involving a QA agency in your black box testing

Generally, you use black box testing methods to test the functionality and performance of an application from the user's perspective. When it comes to this type of testing, it's a good idea to bring in an outsider.

Here's why a QA agency will give you better outcomes than in-house testers when it comes to the black box approach.

Reduced costs

Cost is one of the main reasons that businesses outsource software testing. Hiring an in-house testing team is pricey, and requires investment in recruiting, onboarding and training. With a QA agency, you're getting the same experience and knowledge at a fraction of the cost, and on a much more flexible basis when it comes to provisioning. You and your team can then spend the saved time and resources on more important tasks like fixing the bugs that surface.

Variance in testing environments

The right QA agency will be up to date with the latest trends, techniques, and software testing tools. Ideally, they'll have broad knowledge and experience across a wide range of technologies on several different devices, systems and platforms. When you want to test your application in a variety of environments and scenarios, a third-party tester is probably the answer.

Unbiased assessment

Hiring QA professionals to perform black box testing often makes sense, as it allows for an unbiased assessment of the software. Developers can find it hard to look objectively at bugs and errors, whereas outside experts are more likely to be impartial. Involving an expert QA agency with a fresh set of eyes is more likely to spot errors and will ensure that the software is put through its paces with rigorous testing.

Talk to an expert, today

There's a time and place to involve third-party expertise and we hope this article has helped you decipher when it's the right time for your business.

If you are considering using a QA agency, we'd love to help. With over 20 years of experience, OnPath Testing is your go-to fountain of testing knowledge. Want to learn more about white box vs black box testing before you make the final decision to outsource? Get in touch today.

Find out more about different software testing methods on our blog.

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