[Regression]Type definition problem with observable

[patheticcockroach]

Description

When "compiling" my TypeScript project, I get the following error with AVA 2.0:

[...]/npm/node_modules/ava/index.d.ts:3:10 - error TS2339: Property 'observable' does not exist on type 'SymbolConstructor'.

3  [Symbol.observable](): ObservableLike;
           ~~~~~~~~~~

Found 1 error.

AVA 1.4.1 used to work fine. I noticed this error when Travis suddenly started to fail (it installs the latest AVA version every time it runs, while locally I update just from time to time).

Test Source

All it takes is the import:

import test from 'ava';

Error Message & Stack Trace

Cf above, that's all I get

Config

I don't have anything special for AVA's config in package.json, all I have is this part:

{
  "scripts": {
    "test": "ava ./tests/*.js -v -s"
  },
}

Command-Line Arguments

Just compiling, no arguments:

tsc

Here's my tsconfig.json though:

{
  "compileOnSave": true,
  "compilerOptions": {
    "target": "es5",
    "allowSyntheticDefaultImports": true,
    "noImplicitAny" : true,
    "strictPropertyInitialization": false,
    "strictNullChecks": true,
    "esModuleInterop": true,
    "lib": [
      "es5",
      "es2015.promise",
      "esnext.asynciterable"
    ],
    "skipLibCheck": false,
    "alwaysStrict": true,
    "removeComments": true,
    "typeRoots": [
      "node_modules/@types",
      "../node_modules/@types"
    ],
    "moduleResolution": "node",
    "baseUrl": ".",
    "paths": {
      "*": [
        "*",
        "[...]/npm/node_modules/*",
        "/usr/local/lib/node_modules/*"
      ]
    }
  },
  "exclude": [
    "node_modules"
  ]
}

Relevant Links

Found a similar issue here on another project. Apparently it's because @types/node is required. If I install it, it does work. The previously-mentioned issue was solved by doing this.

Environment

Locally Win 10 x64, Node 10.16.0 LTS, AVA 2.0.0
Remotely, whatever Travis runs (some Linux, same Node and AVA version)

[sindresorhus]

Why are you not using @types/node? AVA is a Node.js test runner. Tests are Node.js scripts.

[patheticcockroach]

Well, this particular project contains multiple micro-services, with the top folder containing common dev dependencies. Like this:

- project_root
  |- node_module
    |- @types
      |- node
  |- service_1
    |- node_modules
  |- /service_2
    |- node_modules

@types/node is actually in the ../node_modules folder that you see mentioned in typeRoots in tsconfig.json. Which used to cause no issue. Now, compiling from the top still works, but compiling from subfolders doesn't anymore (unless I install @types/node in each of them)

[novemberborn]

@types/node is actually in the ../node_modules folder that you see mentioned in typeRoots in tsconfig.json. Which used to cause no issue. Now, compiling from the top still works, but compiling from subfolders doesn't anymore (unless I install @types/node in each of them)

I imagine you can tweak your tsconfig.json to work better for monorepos, or you can extend a parent config to share the types. But I've never done this before.

(I'm closing this issue for housekeeping purposes, but let's keep the conversation going.)

[ashleyw]

It seems like observable is not a property of SymbolConstructor in Node 8:

https://github.com/phra/DefinitelyTyped/blob/e22898d5b679ae1fe06d75344b4440a839835455/types/node/v8/index.d.ts

Does this mean Ava no longer supports Node 8?

[patheticcockroach]

Oops, looks like I overlooked the previous reply notification 😕
I'm not really a Node package specialist, but shouldn't packages be able to run on their own, without making any assumption on whether or not a project that uses them also includes, by itself, dependencies that they require?

[novemberborn]

I'm not really a Node package specialist, but shouldn't packages be able to run on their own, without making any assumption on whether or not a project that uses them also includes, by itself, dependencies that they require?

Yes, but TypeScript plays by different rules.

[znorman-harris]

I'm having the exact same issue with a very similar setup just trying to compile typescript - several projects all in the same repository and all are using typescript.

I just saw that someone had a "workaround" from the mention above which solved the immediate problem for me right now.

bitjson/typescript-starter#221 (comment)

Some basic notes on my environment:

• node: 10.17.0
• ava 2.4.0
• typescript 3.7.4

project root
| client
\ ava tests and other code
| server
\ ava tests and other code

Originally, I was having this issue in my server folder, but I switched to webpack to minify and no longer have the issue unless I use tsc -b. I'm now having this issue in my client folder because I need to compile the typescript to run the tests (it is for a VSCode extension). Running tests as documented is fine since it loads the ts files on the fly.

[tvkit]

I decided to lock into patch-level updating using the tilde constraint:

"ava": "~2.2.0",

instead of the caret that permitted the problematic 2.4 update:

"ava": "^2.2.0",

I inadvertently ran yarn against the project causing a variety of unexpected updates.