Describe the bug

This is a Vite bug that affects Vitest.

vite:html-inline-proxy plugin is supposed to resolve requests for module scripts from index.html, but it fails to do so in some environments. The issue is that this plugin expects URL to include ?html-proxy, but in some cases the URL instead includes ?v=12535af4&html-proxy, causing regex to not match, and thus request fails to resolve correctly. See Explanation section below for more details.

Reproduction

https://github.com/maxpatiiuk/vite-html-proxy-bug

Steps to reproduce

1. Clone this repository

   git clone https://github.com/maxpatiiuk/vite-html-proxy-bug
   cd vite-html-proxy-bug

2. Install dependencies

   npm install

3. Run vitest browser mode

   npx vitest

   See the following error message in the terminal:

10:42:08 AM [vite] Pre-transform error: Failed to parse source for import analysis because the content contains invalid JS syntax. You may need to install appropriate plugins to handle the .js file format, or if it's an asset, add "**/*.js" to `assetsInclude` in your configuration.
10:42:08 AM [vite] Internal server error: Failed to parse source for import analysis because the content contains invalid JS syntax. You may need to install appropriate plugins to handle the .js file format, or if it's an asset, add "**/*.js" to `assetsInclude` in your configuration.
  Plugin: vite:import-analysis
  File: /Users/mak13180/site/esri/vite-html-proxy-bug/node_modules/@vitest/browser/dist/client/tester/tester.html?v=0aab3063&html-proxy&index=0.js:7:41
  5  |      <link rel="icon" href="proxy.php?url=https%3A%2F%2Fredirect.github.com%2F%7B__VITEST_FAVICON__%7D" type="image/svg+xml">
  6  |      <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  7  |      <title>Vitest Browser Tester</title>
     |                                          ^
  8  |      <script type="module" crossorigin src="proxy.php?url=https%3A%2F%2Fredirect.github.com%2F__vitest_browser__%2Ftester-B8eJg1-s.js"></script>
  9  |      <link rel="modulepreload" crossorigin href="proxy.php?url=https%3A%2F%2Fredirect.github.com%2F__vitest_browser__%2Futils-CaCTRFti.js">
      at TransformPluginContext._formatError (file:///Users/mak13180/site/esri/vite-html-proxy-bug/node_modules/vite/dist/node/chunks/dep-CB_7IfJ-.js:49255:41)
      at TransformPluginContext.error (file:///Users/mak13180/site/esri/vite-html-proxy-bug/node_modules/vite/dist/node/chunks/dep-CB_7IfJ-.js:49250:16)
      at TransformPluginContext.transform (file:///Users/mak13180/site/esri/vite-html-proxy-bug/node_modules/vite/dist/node/chunks/dep-CB_7IfJ-.js:63993:14)
      at async PluginContainer.transform (file:///Users/mak13180/site/esri/vite-html-proxy-bug/node_modules/vite/dist/node/chunks/dep-CB_7IfJ-.js:49096:18)
      at async loadAndTransform (file:///Users/mak13180/site/esri/vite-html-proxy-bug/node_modules/vite/dist/node/chunks/dep-CB_7IfJ-.js:51929:27)
      at async viteTransformMiddleware (file:///Users/mak13180/site/esri/vite-html-proxy-bug/node_modules/vite/dist/node/chunks/dep-CB_7IfJ-.js:61881:24)

Explanation

Starting with Vitest 2.1.5, Vitest browser mode calls transformIndexHtml.

If html contains module scripts, preTransformRequest will be called:

The request URL may look like /Users/mak13180/site/esri/arcgis-dashboards/node_modules/@vitest/browser/dist/client/tester/tester.html?html-proxy&index=0.js

Later, ensureVersionQuery is called to add version hash to query string:

The updated URL: /Users/mak13180/site/esri/arcgis-dashboards/node_modules/@vitest/browser/dist/client/tester/tester.html?v=12535af4&html-proxy&index=0.js

Such URL is supposed to be resolved by the vite:html-inline-proxy plugin:

Here is the bug: the regex that checks for html-proxy URLs expects the URL to contain ?html-proxy, where as the above URL contains &html-proxy:

Because of that, pluginContainer.load(id) fails to resolve the file. In such cases, it falls back to reading the file from the file system:

fs.readFile() ignores the query string, reads the tester.html file, and serves it - however, the .js file was expected. This causes an error in the Pre-transform during import analysis.

Solution

Vite should update the following regexes:

Should replace \? by [?&].

For reference, this is already correct in the vite:css-post plugin:

Also, the Vite team should evaluate whether this bug affects any other Vite plugins.

System Info

System:
    OS: macOS 15.2
    CPU: (10) arm64 Apple M1 Pro
    Memory: 702.52 MB / 32.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 22.12.0 - ~/.local/state/fnm_multishells/98022_1737052578656/bin/node
    Yarn: 1.22.19 - ~/.local/state/fnm_multishells/98022_1737052578656/bin/yarn
    npm: 10.9.0 - ~/.local/state/fnm_multishells/98022_1737052578656/bin/npm
    pnpm: 8.9.0 - ~/.local/state/fnm_multishells/98022_1737052578656/bin/pnpm
  Browsers:
    Chrome: 131.0.6778.265
    Safari: 18.2
  npmPackages:
    vite: ^5.2.0 => 5.4.11 

Reproducible in `@vitest/browser` in 2.1.5 and above including 3.0.0 (related commit: https://github.com/vitest-dev/vitest/commit/169028f03abf5e80d77924f4ed9ae6107647c4c0). Not reproducible in 2.1.3 as transformIndexHtml wasn't called in that version.

Reproducible with Playwright and default provider in headless and headed mode in Chrome and Chromium. Reproducible with yarn monorepo and npm.

Used Package Manager

npm

Logs

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