Regression with `find()` generic type about ember-test-helpers

[chriskrycho]

While I understand your POV, this is strictly not a regression, it's an intentional change in the type to match the actual behavior. There is no way for find() to actually provide something of that type, so we are not going to ship a type definition which pretends it does.

While folks often use generics/type params like this as a convenient way to do a cast, there's a very good reason that most ESLint (and historically also TSLint!) rule sets forbid generic types which constrain the return type without any relation to an input parameter. That reason is: it is literally always a lie for a generic to appear on a call expression like this other than a constructor type (where it is narrowing what you can do with the returned type from an otherwise unconstrained default). Net: this was always an inappropriate use of a generic parameter.

To be clear: I understand why you might find the decrease in convenience annoying, especially in tests. But it's not a regression, and we're not going to revert it.

(And no, shipping something stronger than TS does is not necessarily "overly opinionated": TS has to balance not breaking every single piece of DOM code using TS out there against correctness, and they might well make different decisions today if starting from scratch!)