ava 0.17.0 with FlowType 0.35.0 results in type-ambiguity errors

[jokeyrhyme]

Description

Trying to update a project to use ava 0.17.0

For what seem like pretty standard-looking ava tests to me (as far as I know), FlowType is getting all up in my face about some ambiguity relating to the new types that ava declares. I am obviously quite scandalised by all this. Oh my!

Test Source

This is the test code in question:

test('A, A->B, B->C, BC->end', (t) => {
  const tasks = [
    { fn: noop, id: 'a', label: 'a', requires: [ 'B', 'C' ] },
    { fn: noop, id: 'b', label: 'b', provides: [ 'C' ], requires: [ 'B' ] },
    { fn: noop, id: 'c', label: 'c', provides: [ 'B' ], requires: [ 'A' ] },
    { fn: noop, id: 'd', label: 'd', provides: [ 'A' ] }
  ]
  t.notThrows(() => tasks.sort(compareByMetadata))
  const ids = tasks.map((task) => task.id)
  t.deepEqual(ids, [ 'd', 'c', 'b', 'a' ])
})

Error Message & Stack Trace

When I run flow_check, I get 23 errors that are all very similar, like this:

test/sort-tasks.js:63
 63: test('A, A->B, B->C, BC->end', (t) => {
     ^ function call. Could not decide which case to select
201: declare module.exports: {
                             ^ callable object type. See: node_modules/ava/index.js.flow:201
  Case 2 may work:
  203: 	(name: string, run: ContextualTest): void;
       	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ function type. See: node_modules/ava/index.js.flow:203
  But if it doesn't, case 4 looks promising too:
  205: 	(name: string, run: Macros<ContextualTestContext>, ...args: Array<any>): void;
       	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ function type. See: node_modules/ava/index.js.flow:205
  Please provide additional annotation(s) to determine whether case 2 works (or consider merging it with case 4):
   63: test('A, A->B, B->C, BC->end', (t) => {
                                            ^ return

Config

Copy the relevant section from package.json:

{
  "ava": {}
}

Command-Line Arguments

Copy your npm build scripts or the ava command used:

nyc ava

Relevant Links

• https://github.com/jokeyrhyme/node-init.js

Environment

Node.js v7.1.0
darwin 16.3.0
ava 0.17.0
npm 4.0.2

[sindresorhus]

@thejameskyle halp

[jokeyrhyme]

@sindresorhus that kitten slays me every time. So cute! Your participation in any GitHub conversation is a welcome presence. :D

[jfmengels]

I am getting the same error and can't seem to find a solution to it (except removing the macro possibility...) 🤔

[jokeyrhyme]

I did get this working by explicitly annotating the types, something like this:

/* :: import type { ContextualTest } from 'ava' */
test('my test', (t) => { t.pass('yay') } /* : ContextualTest */)

But I don't want to have to do this for every single test.

Another interim solution would be to tell FlowType to ignore ava. /shrug

[jokeyrhyme]

Just FYI: I'm having this issue with FlowType 0.36.0, too.

[mymattcarroll]

Another FYI: Having the same issue with flow-bin@0.37.0

[jokeyrhyme]

Oooo, nice work! Yay! <3

[btipling]

Is this released yet? I still get this problem.

[jokeyrhyme]

@btipling most recent release looks like 0.17.0 2016-11-17, whilst this was only merged 2016-12-25