你如何使用 yarn typescript 和 jest 将 yarn workspace monorepo 更新到节点 18？

Question

This year (2023) support for Node 14 and 16 ends. So we chose to migrate to 18. This migration issue is from a yarn 2 workspace monorepo running node 14 to a yarn 3 workspace monorepo running node 18.

The first issue we ran into is this:

TypeError: BigInt.prototype.toString requires that 'this' be a BigInt

Answer 1

You can't run node 18 and yarn 2 with workspaces, you need to go to yarn 3. Getting to yarn 3 is not that hard, but getting jest to play nice is where your issues will be. Here is a path forward.

Typescript

Start with your types. Update to the latest version, and fix all your type errors. Node 18 typescript is not as forgiving as Node 14. Things will outright fail without helpful errors. This will probably improve with future versions. But right now things will fail for no apparent reason, and it will be some type error buried. Best to fix all your type warnings before you even start. This includes in your test files.

Babel

If you are not on Babel 7 you might want to get there. You will probably need babel to get jest working. https://babeljs.io/docs/v7-migration

Also a good resource is the monorepo instructions here: https://babeljs.io/docs/config-files#file-relative-configuration

If you are like me and your project has some experimental stuff in it you may need some extra stuff in your babel config. But it depends on the scope of your project. Mine ended up looking about like this:

{
  "presets": [
    ["@babel/preset-env", { "targets": { "node": "current" } }],
    "@babel/preset-typescript"
  ],
  "plugins": [
    ["@babel/plugin-proposal-decorators", { "legacy": true }],
    ["@babel/plugin-proposal-class-properties", { "loose": true }]
  ]
}

Jest

As of this writing @types/jest does not play nice with yarn 3 and node 18. @types/jest is convenient, but it will throw errors and warnings. It is actually not supported by Jest, it is a 3rd party library. The solution is to use "@jest/globals". It gives warnings if you attempt to implement it globally. It is probably possible to implement globally, but it might just be easier to grab a JR dev and tell them to import the jest variables into each test file. So go ahead and remove "@types/jest".

import { jest, describe, it, expect, beforeEach ... whatever else } from '@jest/globals"

Likewise "ts-jest" does not play nice as well. I could not get all the tests working until I went with the jest babel implementation. I recommend removing ts-jest as well.

Use the "Via babel" instructions from here: https://jestjs.io/docs/getting-started#using-typescript

Also a good read is the "Type definitions" section on the same page.

Yarn 2 => 3

Yarn 2 is not supported on node 18 for yarn workspaces. To be able to continue to use yarn, you probably will have to update to yarn 3. You can use "yarn set version" to update to yarn 3. https://yarnpkg.com/cli/set/version

Depending on your project you may need to be sure that corepack is enabled. If you set your yarn version to 3, and you are running node 18, and yarn still says version 1, it is probably missing corepack. https://yarnpkg.com/getting-started/install

As of April 2023: These commands should work to update to yarn 3:

// Update to latest

yarn set version stable

// Update workspace tools.

yarn plugin import @yarnpkg/plugin-workspace-tools

// Clean the cache out of all your workspaces

yarn workspaces focus --all --production && rm -rf "$(yarn cache clean)"

From here you should be past the major obstacles and you will probably just need to clean up some tests.

Hope this helps you spend less time digging through docs, and get your project up and working.