From ebf39a04329ddc6ba765e006a5d463680a952270 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E7=BF=A0?= <green@sapphi.red>
Date: Tue, 19 May 2026 13:54:40 +0900
Subject: [PATCH] test(css): sass does not use main field (#22449)

---
 .../src/node/__tests__/plugins/css.spec.ts    | 32 +++++++++++++++++++
 .../sass-package-resolution/.gitignore        |  1 +
 .../sass-pkg-with-index/index.scss            |  3 ++
 .../sass-pkg-with-index/main.scss             |  3 ++
 .../sass-pkg-with-index/package.json          |  6 ++++
 packages/vite/src/node/plugins/css.ts         |  6 ++--
 6 files changed, 49 insertions(+), 2 deletions(-)
 create mode 100644 packages/vite/src/node/__tests__/plugins/fixtures/sass-package-resolution/.gitignore
 create mode 100644 packages/vite/src/node/__tests__/plugins/fixtures/sass-package-resolution/node_modules/sass-pkg-with-index/index.scss
 create mode 100644 packages/vite/src/node/__tests__/plugins/fixtures/sass-package-resolution/node_modules/sass-pkg-with-index/main.scss
 create mode 100644 packages/vite/src/node/__tests__/plugins/fixtures/sass-package-resolution/node_modules/sass-pkg-with-index/package.json

diff --git a/packages/vite/src/node/__tests__/plugins/css.spec.ts b/packages/vite/src/node/__tests__/plugins/css.spec.ts
index 9f06607b0648f1..d925ee96a45dc8 100644
--- a/packages/vite/src/node/__tests__/plugins/css.spec.ts
+++ b/packages/vite/src/node/__tests__/plugins/css.spec.ts
@@ -6,6 +6,7 @@ import { resolveConfig } from '../../config'
 import type { InlineConfig } from '../../config'
 import {
   convertTargets,
+  createCSSResolvers,
   cssPlugin,
   cssUrlRE,
   getEmptyChunkReplacer,
@@ -15,6 +16,7 @@ import {
   resolveLibCssFilename,
 } from '../../plugins/css'
 import { PartialEnvironment } from '../../baseEnvironment'
+import { normalizePath } from '../../utils'
 
 const dirname = import.meta.dirname
 
@@ -421,6 +423,36 @@ describe('preprocessCSS', () => {
   })
 })
 
+// Sass does not consult the `main` field; see
+// https://sass-lang.com/documentation/js-api/classes/nodepackageimporter/
+describe('sass package resolution', () => {
+  const fixtureRoot = path.resolve(dirname, 'fixtures/sass-package-resolution')
+  const importer = path.resolve(fixtureRoot, 'entry.scss')
+
+  async function getSassResolver() {
+    const config = await resolveConfig(
+      { configFile: false, root: fixtureRoot },
+      'serve',
+    )
+    const environment = new PartialEnvironment('client', config)
+    const resolvers = createCSSResolvers(config)
+    return (id: string) => resolvers.sass(environment, id, importer)
+  }
+
+  test('resolves to index.scss at package root, ignoring main field', async () => {
+    const resolve = await getSassResolver()
+    const resolved = await resolve('sass-pkg-with-index')
+    expect(resolved).toBe(
+      normalizePath(
+        path.resolve(
+          fixtureRoot,
+          'node_modules/sass-pkg-with-index/index.scss',
+        ),
+      ),
+    )
+  })
+})
+
 describe('resolveLibCssFilename', () => {
   test('use name from package.json', () => {
     const filename = resolveLibCssFilename(
diff --git a/packages/vite/src/node/__tests__/plugins/fixtures/sass-package-resolution/.gitignore b/packages/vite/src/node/__tests__/plugins/fixtures/sass-package-resolution/.gitignore
new file mode 100644
index 00000000000000..2b9b8877da603f
--- /dev/null
+++ b/packages/vite/src/node/__tests__/plugins/fixtures/sass-package-resolution/.gitignore
@@ -0,0 +1 @@
+!/node_modules/
diff --git a/packages/vite/src/node/__tests__/plugins/fixtures/sass-package-resolution/node_modules/sass-pkg-with-index/index.scss b/packages/vite/src/node/__tests__/plugins/fixtures/sass-package-resolution/node_modules/sass-pkg-with-index/index.scss
new file mode 100644
index 00000000000000..06f82754b691b0
--- /dev/null
+++ b/packages/vite/src/node/__tests__/plugins/fixtures/sass-package-resolution/node_modules/sass-pkg-with-index/index.scss
@@ -0,0 +1,3 @@
+.from-index {
+  color: navy;
+}
diff --git a/packages/vite/src/node/__tests__/plugins/fixtures/sass-package-resolution/node_modules/sass-pkg-with-index/main.scss b/packages/vite/src/node/__tests__/plugins/fixtures/sass-package-resolution/node_modules/sass-pkg-with-index/main.scss
new file mode 100644
index 00000000000000..c944e6403a3c8a
--- /dev/null
+++ b/packages/vite/src/node/__tests__/plugins/fixtures/sass-package-resolution/node_modules/sass-pkg-with-index/main.scss
@@ -0,0 +1,3 @@
+.from-main {
+  color: red;
+}
diff --git a/packages/vite/src/node/__tests__/plugins/fixtures/sass-package-resolution/node_modules/sass-pkg-with-index/package.json b/packages/vite/src/node/__tests__/plugins/fixtures/sass-package-resolution/node_modules/sass-pkg-with-index/package.json
new file mode 100644
index 00000000000000..a44811ac1b9c6f
--- /dev/null
+++ b/packages/vite/src/node/__tests__/plugins/fixtures/sass-package-resolution/node_modules/sass-pkg-with-index/package.json
@@ -0,0 +1,6 @@
+{
+  "name": "sass-pkg-with-index",
+  "private": true,
+  "version": "1.0.0",
+  "main": "main.scss"
+}
diff --git a/packages/vite/src/node/plugins/css.ts b/packages/vite/src/node/plugins/css.ts
index 7a271f93e7f90a..cf6152c9eb8ae2 100644
--- a/packages/vite/src/node/plugins/css.ts
+++ b/packages/vite/src/node/plugins/css.ts
@@ -1283,13 +1283,15 @@ export function getEmptyChunkReplacer(
 
 const fileURLWithWindowsDriveRE = /^file:\/\/\/[a-zA-Z]:\//
 
-interface CSSAtImportResolvers {
+export interface CSSAtImportResolvers {
   css: ResolveIdFn
   sass: ResolveIdFn
   less: ResolveIdFn
 }
 
-function createCSSResolvers(config: ResolvedConfig): CSSAtImportResolvers {
+export function createCSSResolvers(
+  config: ResolvedConfig,
+): CSSAtImportResolvers {
   let cssResolve: ResolveIdFn | undefined
   let sassResolve: ResolveIdFn | undefined
   let lessResolve: ResolveIdFn | undefined