Resolving hoisted `typeRoots` paths

TypeScript Version: 3.6.2

Search Terms:

• resolve typeRoots in parent package node_modules
• sharing tsconfig in yarn workspaces
• use hoisted tsconfig in child package

Code

I've set up a Lerna monorepo which uses Yarn Workspaces. Within this monorepo is a config package, which other packages depend on. This config package has @types/node and @types/jest as dependencies.

From sibling packages, the shared config is used like so:

{
  "extends": "@project/config/ts.json",
  "include": ["src", "tests"],
  "compilerOptions": {
    "outDir": "lib"
  }
}

In the shared config, I point to the appropriate types root:

{
  "compilerOptions": {
    // ...
    "typeRoots": ["node_modules/@types"]
  }
}

However, within the shared config package, @types/* have been hoisted from the local node_modules to the monorepo's top-level node_modules. This behavior is usually fine given node's resolution... but it seems the config does not resolve to its parent's node_modules.

Expected behavior:

For the specified type root to resolve to the parent's node_modules

Actual behavior:

Tests fail with messages such as Cannot find name 'describe'. Do you need to install type definitions for a test runner? ...

One workaround:

{
  "compilerOptions": {
    // ...
    "typeRoots": ["../../node_modules/@types"]
  }
}

This workaround isn't very clean. Lerna & Yarn definitely pose some complexity for type root resolution. Hopefully resolving parents is considered a worthwhile modification.

Please let me know. Thank you :)

TypeScript 3.6.2 または typescript@next を使用して、共有設定の typeRoots と兄弟パッケージの extends 設定を使う Lerna と Yarn Workspaces のセットアップを再現します。まず、共有設定から相対パス node_modules/@types がどのように解決されるかを追跡し、次に hoist された親パッケージの型定義が見つかり、describe が見つからないエラーが発生しなくなることを確認します。