WIP: Add array-type rule

[macklinu]

I'd like to contribute the array-type rule in #5, but I'm running into issues. None of my console.log statements are being hit, so the nodes don't seem to be visited. All of my invalid test cases should pass (in theory), but they are all currently failing.

Here's an AST Explorer with the test cases I have, if you'd like to check out the AST.

Why aren't these nodes being visited? Any suggestions on how to approach checking type annotations?

[bradzacher]

OOOOOOkaaay.
I did some digging.
A lot of digging.
I setup debugging locally and explored how exactly eslint decides to traverse nodes and their children.

I've outlined the problem here: eslint/typescript-eslint-parser#532
The TL;DR is that eslint doesn't know about Identifier's typeAnnotation property, so it doesn't traverse it.

You'll notice in no-explicit-any explicitly defines an Identifier selector, which manually traverses typeAnnotation: https://github.com/nzakas/eslint-plugin-typescript/blob/master/lib/rules/no-explicit-any.js#L89-L95

So to make this work, you'll have to do the same!

[armano2]

@macklinu are you planning to finish this rule?

[armano2]

@bradzacher do you mind if i take this one over?

looks like @macklinu is not interested in finishing it

[bradzacher]

@armano2 no response doesn't mean not interested. Just means they're busy on other priorities!

I'm not going to stand in the way of progress (and I'm sure @macklinu would be happy for you to commandeer his work if he has other priorities atm)

[armano2]

@bradzacher that's what i meant, i put it in wrong words 👍