Flow type definition

We already have a great TypeScript definition. We should have one for Flow too! Both of these type checkers are awesome and we shouldn’t play favorites. This would also be interesting comparison wise.

Anyone familiar with Flow willing to contribute this?

// @thejameskyle

The TypeScript definition is actually partly generated (https://github.com/avajs/ava/pull/884) because it was too tedious to define the chainable test API manually. For example: test.cb.serial.skip(). The properties can be in any order. I wonder if that is needed for Flow too.

[jamiebuilds]

Okay so I was planning on just playing around with it but you nerd sniped me and I ended up doing the entire type definition.

I was not prepared for how big the generated TypeScript .d.ts file is. I spent a long time trying to deduce what the API limitations were from that API. But then I started exploring the actual implementation in AVA and that was much easier to understand.

One of the things that I thought was unusual with the TypeScript definition you generate is that it reduces the API methods down to act like they can’t chain forever despite option-chain supporting the ability to chain infinitely. I ignored that piece because it seemed unimportant and that it would only serve to greatly complicate the type definition, not to mention now it’s matching what happens at the runtime.

It also adds support for .always since I noticed that was missing from the TypeScript definition.

Anyways here is the current state of the definition, I’m happy to say it’s only like 200 lines compared to the 1,200 line TypeScript definition: https://gist.github.com/thejameskyle/6a0f4d2ef41ed3a7554ce1fa208ae291

I’m sure it has a handful of issues, I haven’t really done that much testing of it, I’ve just been keeping a lot of it in my head.

[jamiebuilds]

Also, people keep taking this as a comparison between Flow and TypeScript. I wasn’t bragging about Flow, I was bragging about my own mad skillz trying to figure out that crazy type definition.