The WHATWG and the W3C have been moving in a very different direction, treating testing as a major part of spec development, because the goal is to get implemen

The WHATWG and the W3C have been moving in a very different direction, treating testing as a major part of spec development, because the goal is to get implementations of the specifications, and how do you determine that if not by testing. https://blog.whatwg.org/improving-interoperability https://blog.whatwg.org/improving-interoperability is a post from the WHATWG side about this, and the outcome isn't just the direct "it's easier to write code against tests" but also "it's easier to notice when the spec changes" (because you now get a failing test).