fix(vite-node): normalize drive letter to keep the same reference to a module

packages/vite-node/src/utils.ts

@@ -6,6 +6,15 @@ import type { Arrayable, Nullable } from './types'
 
 export const isWindows = process.platform === 'win32'
 
+const drive = isWindows ? process.cwd()[0] : null
+const driveOpposite = drive
+  ? (drive === drive.toUpperCase()
+      ? drive.toLowerCase()
+      : drive.toUpperCase())
+  : null
+const driveRegexp = drive ? new RegExp(`(?:^|/@fs/)${drive}(\:[\\/])`) : null
+const driveOppositeRegext = driveOpposite ? new RegExp(`(?:^|/@fs/)${driveOpposite}(\:[\\/])`) : null
+
 export function slash(str: string) {
   return str.replace(/\\/g, '/')
 }
@@ -16,6 +25,10 @@ export function normalizeRequestId(id: string, base?: string): string {
   if (base && id.startsWith(base))
     id = `/${id.slice(base.length)}`
 
+  // keep drive the same as in process cwd
+  if (driveRegexp && !driveRegexp?.test(id) && driveOppositeRegext?.test(id))
+    id = id.replace(driveOppositeRegext, `${drive}$1`)
+
   return id
     .replace(/^\/@id\/__x00__/, '\0') // virtual modules start with `\0`
     .replace(/^\/@id\//, '')

test/core/src/esm/esm.js

@@ -0,0 +1 @@
+export const test = 1

test/core/src/esm/package.json

@@ -0,0 +1,3 @@
+{
+  "type": "module"
+}

test/core/test/imports.test.ts

@@ -1,6 +1,7 @@
 import { mkdir, writeFile } from 'node:fs/promises'
+import { fileURLToPath } from 'node:url'
 import { resolve } from 'pathe'
-import { describe, expect, test } from 'vitest'
+import { describe, expect, test, vi } from 'vitest'
 import { dynamicRelativeImport } from '../src/relative-import'
 
 // @ts-expect-error module is not typed
@@ -130,3 +131,34 @@ describe('importing special files from node_modules', async () => {
     expect(mod.default).toBe('/src/node_modules/file.mp3')
   })
 })
+
+describe.runIf(process.platform === 'win32')('importing files with different drive casing', async () => {
+  test('importing a local file with different drive casing works', async () => {
+    const path = new URL('./../src/timeout', import.meta.url)
+    const filepath = fileURLToPath(path)
+    const drive = filepath[0].toLowerCase()
+    const upperDrive = drive.toUpperCase()
+    const lowercasePath = filepath.replace(`${upperDrive}:`, `${drive}:`)
+    const uppercasePath = filepath.replace(`${drive}:`, `${upperDrive}:`)
+    expect(lowercasePath).not.toBe(uppercasePath)
+    const mod1 = await import(lowercasePath)
+    const mod2 = await import(uppercasePath)
+    const mod3 = await import('./../src/timeout')
+    expect(mod1).toBe(mod2)
+    expect(mod1).toBe(mod3)
+  })
+
+  test('importing an external file with different drive casing works', async () => {
+    const path = new URL('./../src/esm/esm.js', import.meta.url)
+    const filepath = fileURLToPath(path)
+    const drive = filepath[0].toLowerCase()
+    const upperDrive = drive.toUpperCase()
+    const lowercasePath = filepath.replace(`${upperDrive}:`, `${drive}:`)
+    const uppercasePath = filepath.replace(`${drive}:`, `${upperDrive}:`)
+    expect(lowercasePath).not.toBe(uppercasePath)
+    const mod1 = await import(lowercasePath)
+    vi.resetModules() // since they reference the same global ESM cache, it should not matter
+    const mod2 = await import(uppercasePath)
+    expect(mod1).toBe(mod2)
+  })
+})

test/core/vitest.config.ts

@@ -66,7 +66,7 @@ export default defineConfig({
       seed: 101,
     },
     deps: {
-      external: ['tinyspy', /src\/external/],
+      external: ['tinyspy', /src\/external/, /esm\/esm/],
       inline: ['inline-lib'],
       moduleDirectories: ['node_modules', 'projects', 'packages'],
     },