White-box testing The real point is that tests are usually designed from an abstract structure such as the input space, a graph, or logical predicates, and the question is what level of abstraction we derive that abstract structure from. That can be the source code, requirements, input space descriptions, or one of dozens of types of design models. Therefore, the "white-box / black-box" distinction is less important and the terms are less relevant. In penetration testing, white-box testing refers to a methodology where a white hat hacker has full knowledge of the system being attacked. The goal of a white-box penetration test
Severin Hacker that that it would be accessible for non-English speakers. They felt that automated translation software wasn't as effective as using the skills and knowledge of bilingual speakers. During Hacker's doctoral studies, Duolingo became a by-product of this idea, or "happy mistake." Hacker's goal for Duolingo was to make it "100% free" so the most disadvantaged person with an internet connection would still have access to it. Hacker and his team of PhD students used machine learning to personalize Duolingo to each user. Specifically, they wanted to predict what language concepts the user was on the verge of forgetting. In 2012,