Isolated DB throws this error `TypeError: The "eventTargets" argument must be an instance of EventEmitter or EventTarget. Received an instance of AbortSignal` with `npx vitest`

まず npx vitest を実行し、db-setup.ts を読んで、単独で発生する DB の失敗を再現します。リンクされた execa issue を確認して AbortSignal と setMaxListeners の背景を把握し、その後、選択した修正によって jsdom 環境でこの TypeError なしにテストスイートを実行できることを確認します。

npx vitest throws the following error "TypeError: The "eventTargets" argument must be an instance of EventEmitter or EventTarget. Received an instance of AbortSignal" with Isolated DB for testing.

A little bit of google searching landed me here, which is the root cause of the problem. You can check out the link for more context. Apparently, execa version 9 which is the current version of the package in the project relies on setMaxListeners export from node:events which throws error in jsdom environment because the AbortSignal from jsdom's AbortController is not node.js EventTarget.

I'm not exactly sure the best way to fix this problem. Of course, one option would be to downgrade execa to version 8 but not sure if that's a good idea based on this comment. However, I added this hack in the db-setup.ts file and it does work for me:

const kEventTarget = Symbol.for('nodejs.event_target') // https://github.com/nodejs/node/blob/68c9f554ffa2fab1ef3b6466c51491371f0dd158/lib/internal/event_target.js#L50

if (globalThis.window !== undefined) {
	const JSDOMAbortController = window.AbortController
	window.AbortController = class extends JSDOMAbortController {
		get signal() {
			const signal = super.signal
			if ('constructor' in signal) {
				// @ts-expect-error
				signal.constructor[kEventTarget] = true //
			} else {
				// @ts-expect-error
				signal.constructor = { [kEventTarget]: true } //https://github.com/nodejs/node/blob/68c9f554ffa2fab1ef3b6466c51491371f0dd158/lib/internal/event_target.js#L1070
			}
			return signal
		}
	}
}