[testing] Detect dependencies to add to the ssr.noExternal option

[aklinker1]

Feature Request

If you use a module that imports/depends on webextension-polyfill, you must add the module to Vite's ssr.noExternal option in your vitest.config.ts file:

// vitest.config.ts
import { defineConfig } from 'vitest/config';
import { WxtVitest } from 'wxt/testing';

export default defineConfig({
  plugins: [WxtVitest()],
  ssr: {
    noExternal: ["@webext-core/storage"],
  },
})

In this case, @webext-core/storage depends on webextension-polyfill, so it needs to be added.

If you don't add it to ssr, you'll get errors like this:

Caution

Error: This script should only be loaded in a browser extension

In theory, WXT should be able to perform an analysis of your dependencies, and add all of them automatically to ssr, like it does with WXT itself:

wxt/src/core/builders/vite/plugins/webextensionPolyfillMock.ts

Lines 34 to 37 in 86b7162

	ssr: {
	// Inline all WXT modules
	noExternal: ['wxt'],
	},

You can see a list of dependencies that depend on webextension-polyfill using pnpm list webextension-polyfill:

$ pnpm ls webextension-polyfill --depth Infinity
...
wxt 0.16.11-alpha1
└── webextension-polyfill 0.10.0

Not sure if there's an equivalent for other package managers.

Is your feature request related to a bug?

"N/A"

What are the alternatives?

Add better documentation around this requirement, it can be confusing to deal with. Will do both.

Additional context

wxt-dev/wxt-examples#15