Can not run tests when using preact compat alias

wight554 commented 2 years ago

Describe the bug

When package tries to import react by alias, it picks CJS version of preact specific module, which leads to following error:

 FAIL  src/app.test.tsx > should render app
TypeError: Cannot read properties of undefined (reading '__H')
 ❯ l node_modules/preact/hooks/dist/hooks.js:1:201
 ❯ d node_modules/preact/hooks/dist/hooks.js:1:600
 ❯ Object.exports.useRef node_modules/preact/hooks/dist/hooks.js:1:2323
 ❯ d.BrowserRouter [as constructor] node_modules/react-router-dom/umd/react-router-dom.development.js:80:28
 ❯ d.O [as render] ../../../../../../../../../C:/Users/wight/Documents/preact-vitest-repro/node_modules/preact/dist/preact.mjs:1:8158
 ❯ j ../../../../../../../../../C:/Users/wight/Documents/preact-vitest-repro/node_modules/preact/dist/preact.mjs:1:5870
 ❯ w ../../../../../../../../../C:/Users/wight/Documents/preact-vitest-repro/node_modules/preact/dist/preact.mjs:1:2137
 ❯ j ../../../../../../../../../C:/Users/wight/Documents/preact-vitest-repro/node_modules/preact/dist/preact.mjs:1:6138
 ❯ P ../../../../../../../../../C:/Users/wight/Documents/preact-vitest-repro/node_modules/preact/dist/preact.mjs:1:8272
 ❯ ../../../../../../../../../C:/Users/wight/Documents/preact-vitest-repro/node_modules/@testing-library/preact/dist/esm/pure.mjs:52:7

Reproduction

https://github.com/wight554/preact-vitest-repro/

System Info

System:
    OS: Windows 10 10.0.22621
    CPU: (16) x64 AMD Ryzen 7 3700X 8-Core Processor
    Memory: 16.89 GB / 31.93 GB
  Binaries:
    Node: 16.14.0 - c:\program files\nodejs\node.EXE
    Yarn: 1.22.4 - ~\AppData\Roaming\npm\yarn.CMD
    npm: 8.3.1 - c:\program files\nodejs\npm.CMD
  Browsers:
    Chrome: 103.0.5060.114
    Edge: Spartan (44.22621.290.0), Chromium (103.0.1264.49)
    Internet Explorer: 11.0.22621.1
  npmPackages:
    vite: ^3.0.0 => 3.0.0
    vitest: ^0.18.0 => 0.18.0

Used Package Manager

yarn

Validations

[X] Follow our Code of Conduct
[X] Read the Contributing Guidelines.
[X] Read the docs.
[X] Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
[X] Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
[X] The provided reproduction is a minimal reproducible example of the bug.

wight554 commented 2 years ago

I've checked https://github.com/preactjs/compat-alias-package, it seems to have proper exports. Can't really tell why this happens

sheremet-va commented 2 years ago

I see that the error is coming from react-router-dom. Have you tried using deps.inline with it? Currently files inside node_modules are not processed by Vite. They are executed by Native Node without any transforming.

wight554 commented 2 years ago

I see that the error is coming from react-router-dom. Have you tried using deps.inline with it? Currently files inside node_modules are not processed by Vite. They are executed by Native Node without any transforming.

This config:

    deps: {
      inline: ['react-router-dom'],
    }

Produces exactly the same error, with this config:

    deps: {
      inline: true,
    }

I get error:

 FAIL  src/app.test.tsx > should render app
Unknown Error: undefined
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯[1/1]⎯

Test Files  1 failed (1)
     Tests  1 failed (1)
      Time  2.13s (in thread 6ms, 35558.00%)

wight554 commented 2 years ago

Other than react-router-dom I faced this error with styled components and recoil and probably other libraries that rely on react

wight554 commented 2 years ago

Tried https://preactjs.com/guide/v10/getting-started#aliasing-in-rollup instead of alias package - this works in vite, but doesn't work in vitest even with https://github.com/vitest-dev/vitest/pull/1634

sheremet-va commented 2 years ago

Tried https://preactjs.com/guide/v10/getting-started#aliasing-in-rollup instead of alias package - this works in vite, but doesn't work in vitest even with https://github.com/vitest-dev/vitest/pull/1634

Please, read again: Currently files inside node_modules are not processed by Vite. They are executed by Native Node without any transforming.

If deps.inline doesn't work, then it needs investigating. Aliasing WILL NOT WORK, if file is not processed by Vite.

sheremet-va commented 2 years ago

One of the solutions from https://vitejs.dev/guide/ssr.html#ssr-externals:

If you have configured aliases that redirects one package to another, you may want to alias the actual node_modules packages instead to make it work for SSR externalized dependencies. Both Yarn and pnpm support aliasing via the npm: prefix.

wight554 commented 2 years ago

One of the solutions from https://vitejs.dev/guide/ssr.html#ssr-externals:

If you have configured aliases that redirects one package to another, you may want to alias the actual node_modules packages instead to make it work for SSR externalized dependencies. Both Yarn and pnpm support aliasing via the npm: prefix.

tried all possible ways to add react or @preact/compat to deps.inline/ssr.noExternal, this doesn't work, tried these: ['@preact/compat', 'react', 'react-dom', "npm:@preact/compat"] always same error

sheremet-va commented 2 years ago

tried all possible ways to add react or @preact/compat to deps.inline/ssr.noExternal, this doesn't work, tried these: ['@preact/compat', 'react', 'react-dom', "npm:@preact/compat"] always same error

No, Vite recommends defining react inside package.json with npm prefix. Please, follow provided links to yarn or pnpm documentation.

Note: I understand deps.inline throws error, this is unrelated to aliasing.

sheremet-va commented 2 years ago

If I add this to /node_modules/react-router/package.json, everything works fine:

  "exports": {
    ".": {
      "import": "./index.js"
    }
  }

This means that react-router doesn't package their library with Node ESM in mind. I checked they bundle ESM for browser, but it's incompatible with Node, as it doesn't have .mjs extension or package.json with type: module. See more here.

I wan't able to make your reproduction run, so I would recommend opening an issue in react-router package for now, and regenerate their package.json in post install hook.

wight554 commented 2 years ago

I wan't able to make your reproduction run

Weird, yarn install + npx vitest run works fine for me on several devices

I would recommend opening an issue in react-router

The thing is, there at least 4 more libraries in my main project with such issue and dealing with all of those this way takes ages to complete, would be way better to see some workaround (at least temporal)

sheremet-va commented 2 years ago

Weird, yarn install + npx vitest run works fine for me on several devices

I mean, I wasn't able to fix it.

The thing is, there at least 4 more libraries in my main project with such issue and dealing with all of those this way takes ages to complete, would be way better to see some workaround (at least temporal)

I proposed several workarounds. The main problem with all of them I guess is the wrong package.json configuration. You can try and manually setup test.alias for your packages. PR https://github.com/vitest-dev/vitest/pull/1673 should help with the problem, but it won't fix it, if package has wrong package.json, and you will still need to add aliases. Until we merge the PR, alias will only be applied if files are inlined.

wight554 commented 2 years ago

If I add this to /node_modules/react-router/package.json, everything works fine

tried doing this, getting this error:

 FAIL  src/app.test.tsx [ src/app.test.tsx ]Error: No "exports" main defined in C:\Users\wight\Documents\preact-vitest-repro\node_modules\react-router\package.json
 ❯ node_modules/react-router-dom/umd/react-router-dom.development.js:12:121
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯Serialized Error: {
  "code": "ERR_PACKAGE_PATH_NOT_EXPORTED",
}

wight554 commented 2 years ago

Managed to fix most errors in main package codebase by patching package.json files in node_modules 8 files packages (would take months to get it fixed in those in best case), but even this way some packages can not be patched, e.g. this:

Error: No "exports" main defined in C:\Users\wight\Documents\blog-template\node_modules\@mui\system\package.json
 ❯ Object.<anonymous> node_modules/@mui/material/node/styles/adaptV4Theme.js:14:15

package.json of node_modules\@mui\material\styles\package.json
{
  "sideEffects": false,
  "module": "./index.js",
  "main": "../node/styles/index.js",
  "types": "./index.d.ts"
}

definitely needs some workaround

wight554 commented 2 years ago

Upd. was able to force esm for most deps using alias and https://github.com/vitest-dev/vitest/pull/1673 But some dependencies can not into esm at all, e.g. styled-components, see

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ Unhandled Errors ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

Vitest caught 1 unhandled error during the test run. This might cause false positive tests.
Please, resolve all the errors to make sure your tests are not affected.

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ Unhandled Error ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
TypeError: Cannot read properties of null (reading 'context')
 ❯ Module.q ../../../../../../../../../C:/Users/wight/Documents/blog-template/node_modules/preact/hooks/dist/hooks.mjs:1:1014
 ❯ node_modules/styled-components/src/utils/interleave.js:1:18828
 ❯ O node_modules/styled-components/src/utils/interleave.js:1:19499
 ❯ d.t [as constructor] ../../../../../../../../../C:/Users/wight/Documents/blog-template/node_modules/preact/compat/dist/compat.mjs:1:1363
 ❯ d.O [as render] ../../../../../../../../../C:/Users/wight/Documents/blog-template/node_modules/preact/dist/preact.mjs:1:8158
 ❯ I node_modules/preact/dist/preact.js:1:5716
 ❯ b node_modules/preact/dist/preact.js:1:2103
 ❯ I node_modules/preact/dist/preact.js:1:5984
 ❯ b node_modules/preact/dist/preact.js:1:2103
 ❯ I node_modules/preact/dist/preact.js:1:5984

My changes: https://github.com/wight554/blog-template/pull/55/files#diff-6a3b01ba97829c9566ef2d8dc466ffcffb4bdac08706d3d6319e42e0aa6890dd

Is there any way I can force preact to be CJS @sheremet-va, tried aliasing but no luck? Unfortunately most react UI libraries aren't into supporting node native esm, they prefer bundlers to do they work

sheremet-va commented 2 years ago

@wight554 yes, I also tried this MR agains your repro with no luck.

Is there any way I can force preact to be CJS

Unfortunately Vite's resolution algorithm is asynchronous, so it's not possible to reuse it. Maybe you can try and hijack require yourself, using node's module module? If it's successful we can try and find a way to integrate in inside Vitest, maybe under deps.cjs or something.

wight554 commented 2 years ago

@wight554 yes, I also tried this MR agains your repro with no luck.

Is there any way I can force preact to be CJS

Unfortunately Vite's resolution algorithm is asynchronous, so it's not possible to reuse it. Maybe you can try and hijack require yourself, using node's module module? If it's successful we can try and find a way to integrate in inside Vitest, maybe under deps.cjs or something.

I was able to workaround it before by using TS CJS interop https://devblogs.microsoft.com/typescript/announcing-typescript-4-7-beta/#commonjs-interop Used it for '@testing-library/preact', so it imported CJS version of preact https://github.com/vitest-dev/vitest/issues/747#issuecomment-1140225294 But it doesn't works since vite 3 version of vitest:

 FAIL  test/src/components/Header/Header.test.ts > Header > user is authenticated > user menu is opened > logout click > user service success > should set user state to null
 FAIL  test/src/components/Header/Header.test.ts > Header > user is authenticated > user menu is opened > logout click > user service error > should set snackbar state to error
TypeError: Cannot read properties of undefined (reading '__H')
 ❯ p ../../../../../../../../../C:/Users/wight/Documents/blog-template/node_modules/preact/hooks/dist/hooks.mjs:1:158
 ❯ Module._ ../../../../../../../../../C:/Users/wight/Documents/blog-template/node_modules/preact/hooks/dist/hooks.mjs:1:469
 ❯ y.RecoilObserver [as constructor] test/src/testUtils/components/RecoilObserver/RecoilObserver.ts:17:2
     15| }: RenderableProps<RecoilObserverProps<T>>) => {
     16|   const value = useRecoilValueLoadable(node);
     17|   useEffect(() => onChange(async ? value : value.contents), [onChange, async, value]);
       |  ^
     18|   return null;
     19| };
 ❯ y.M [as render] node_modules/preact/dist/preact.js:1:8004
 ❯ I node_modules/preact/dist/preact.js:1:5716
 ❯ b node_modules/preact/dist/preact.js:1:2103
 ❯ I node_modules/preact/dist/preact.js:1:5984
 ❯ b node_modules/preact/dist/preact.js:1:2103
 ❯ I node_modules/preact/dist/preact.js:1:5984
 ❯ b node_modules/preact/dist/preact.js:1:2103

wight554 commented 2 years ago

Upd. was able to fix it by using cjs interop for all 'preact/hooks' (all packages with multiple version) imports and testing library In my case I can fix it on transform stage (I'm using custom transformer), but I'd be happy to see some general solution, e.g. deps.cjsPackages flag that'll do some transforms for imports on vitest side example: https://github.com/wight554/blog-template/pull/55/commits/e9c6659fa05ff972291b36ce65b35e54e712b130

sheremet-va commented 2 years ago

@wight554 cjs interop is the same as using const mod = require('path'), so I don't see why you really want to use it over simple require in this case. The syntax is hideous.

Using require bypasses Vitest entirely, and uses Native Node.js (note, that loader from #1673 will not work in this cases). Please, can you formulate more clearly what you expect from Vitest in this issue?

wight554 commented 2 years ago

@wight554 cjs interop is the same as using const mod = require('path'), so I don't see why you really want to use it over simple require in this case. The syntax is hideous.

Using require bypasses Vitest entirely, and uses Native Node.js (note, that loader from #1673 will not work in this cases). Please, can you formulate more clearly what you expect from Vitest in this issue?

I wonder if it's possible to force configurable deps list to use require instead of import from vitest side E.g. instead of doing changes I made higher I can add ['preact/hooks', '@testing-library/preact'] to some new configuration option like deps.forceCJS: ['preact/hooks', '@testing-library/preact']

i've seen nodejs createRequire, but idk how can I try to add it to vitest https://nodejs.org/api/module.html#modulecreaterequirefilename

sheremet-va commented 2 years ago

i've seen nodejs createRequire, but idk how can I try to add it to vitest https://nodejs.org/api/module.html#modulecreaterequirefilename

Vitest injects require in your files, you can use it directly.

wight554 commented 2 years ago

Upd. was able to fix it by using cjs interop for all 'preact/hooks' (all packages with multiple version) imports and testing library In my case I can fix it on transform stage (I'm using custom transformer), but I'd be happy to see some general solution, e.g. deps.cjsPackages flag that'll do some transforms for imports on vitest side example: wight554/blog-template@e9c6659

managed to achieve same result with

    alias: [
      {
        find: 'preact/hooks',
        replacement: path.resolve(__dirname, './node_modules/preact/hooks/dist/hooks.js'),
      },
      {
        find: '@testing-library/preact',
        replacement: path.resolve(
          __dirname,
          './node_modules/@testing-library/preact/dist/cjs/index.js',
        ),
      },
    ],

this is way more DX friendly it is possible to cover this internally?

wight554 commented 2 years ago

Upd. cleanest solution I was able to implement:

import { createRequire } from 'module';

const require = createRequire(import.meta.url);

    alias: [
      {
        find: 'preact/hooks',
        replacement: require.resolve('preact/hooks'),
      },
      {
        find: '@testing-library/preact',
        replacement: require.resolve('@testing-library/preact'),
      },
    ],

Upd2. Can be splitted to simple:

const generateCjsAlias = (cjsPackages: Array<string>) => {
  const require = createRequire(import.meta.url);

  return cjsPackages.map((p) => ({
    find: p,
    replacement: require.resolve(p),
  }));
};

    alias: [...generateCjsAlias(['preact/hooks', '@testing-library/preact'])],

I don't mind having this in codebase or as separate plugin, but still would be nicer to see smth like this in vitest itself, either way issue can be closed since there's acceptable fix

sheremet-va commented 2 years ago

would be nicer to see smth like this in vitest itself

Vitest has both alias and test.alias config options, what else do you need? How users populate it is not Vitest authority.

wight554 commented 2 years ago

would be nicer to see smth like this in vitest itself

Vitest has both alias and test.alias config options, what else do you need? How users populate it is not Vitest authority.

I meant having a separate option that'll use alias internally to simplify logic, but that's not really necessary

acapro commented 2 years ago

Just a note -> I got it to work with the solution from @wight554 🙏 - but only when combined with https://github.com/preactjs/compat-alias-package

allanpope commented 2 years ago

@acapro got it working as well with the mixture of test.alias and compat alias package.

All my tests pass expect the ones testing custom hooks. Did you have any like that? am using @testing-library/react-hooks and get this error

[log]  ❯ Object.<anonymous> node_modules/@testing-library/react-hooks/lib/dom/pure.js:48:18
[error] Error: Package subpath './test-utils' is not defined by "exports" in node_modules/react-dom/package.json
[log]  ❯ getRenderer node_modules/@testing-library/react-hooks/lib/pure.js:54:12
[log]  ❯ Object.<anonymous> node_modules/@testing-library/react-hooks/lib/pure.js:70:5
[log]  ❯ Object.<anonymous> node_modules/@testing-library/react-hooks/lib/index.js:11:13

[log] Serialized Error: {
  "code": "ERR_PACKAGE_PATH_NOT_EXPORTED",
}

bogas04 commented 1 year ago

I'm facing similar issue with styled-components/native

Error: Cannot find module 'react-native'
Require stack:
- ./styled-components/native/dist/styled-components.native.cjs.js
Serialized Error: {
  "code": "MODULE_NOT_FOUND",
  "requireStack": [
    "./node_modules/styled-components/native/dist/styled-components.native.cjs.js",
  ],
}

styled-components/native internally uses require like so:

// inside styled-components.native.cjs.js
var reactNative = require('react-native');

I'm using an alias for react-native -> react-native-web, but adding test.alias or test.deps.inline didn't help. I guess vite can't transpile this? Manually patching the dependency solves the problem, but it would be nice if vite could override the require inside styled-components/native itself.

// inside styled-components.native.cjs.js
-var reactNative = require('react-native');
+var reactNative = require('react-native-web');

Here's my config:

export default defineConfig({
    plugins: [react()],
    resolve: {
        alias: {
            'react-native': 'react-native-web',
        },
    },
    test: {
        environment: 'jsdom',
        setupFiles: './tests/setup.ts',
    },
});

sheremet-va commented 1 year ago

I guess vite can't transpile this?

Vitest doesn't support aliasing require calls, yes. There is an open issue: https://github.com/vitest-dev/vitest/issues/1910

eaviles commented 1 year ago

I had a similar problem with a require("react") inside one of my dependencies. I was able to get around it by adding a Vitest setup script…

//vitest.config.ts
setupFiles: ['setup.js']

And then in the setup file I manually created an override for the library's React version by changing require.cache:

require('react'); // to force load it
const modulePath = path.join('node_modules', 'react', 'index.js');
const source = path.resolve(__dirname, '..', 'my-lib', modulePath);
const target = path.resolve(__dirname, modulePath);
require.cache[source] = require.cache[target];

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