test: add coverage for ESM external stack trace column numbers with prepareStackTrace

.prettierignore

@@ -1,5 +1,6 @@
 packages/*/CHANGELOG.md
 packages/vite/src/node/ssr/__tests__/fixtures/errors/syntax-error.*
+packages/vite/src/node/ssr/runtime/__tests__/fixtures/esm-external-column-test/index.mjs
 playground-temp/
 dist/
 LICENSE.md

packages/vite/src/node/ssr/runtime/__tests__/fixtures/esm-external-column-test.js

@@ -0,0 +1,7 @@
+import { outer } from '@vitejs/esm-external-column-test'
+
+function userFn() {
+  throw new Error('column test error')
+}
+
+outer(userFn)

packages/vite/src/node/ssr/runtime/__tests__/fixtures/esm-external-column-test/index.mjs

@@ -0,0 +1 @@
+var _padding_______________________; export function outer(fn) { return inner(fn); } function inner(fn) { return fn(); }

packages/vite/src/node/ssr/runtime/__tests__/fixtures/esm-external-column-test/package.json

@@ -0,0 +1,7 @@
+{
+  "name": "@vitejs/esm-external-column-test",
+  "private": true,
+  "type": "module",
+  "version": "0.0.0",
+  "main": "index.mjs"
+}

packages/vite/src/node/ssr/runtime/__tests__/package.json

@@ -8,6 +8,7 @@
   "dependencies": {
     "@vitejs/cjs-external": "link:./fixtures/cjs-external",
     "@vitejs/esm-external": "link:./fixtures/esm-external",
+    "@vitejs/esm-external-column-test": "link:./fixtures/esm-external-column-test",
     "tinyspy": "2.2.0",
     "birpc": "^0.2.19"
   }

packages/vite/src/node/ssr/runtime/__tests__/server-source-maps.spec.ts

@@ -134,4 +134,40 @@ describe('module runner initialization', async () => {
       ]
     `)
   })
+
+  it('esm external stack traces should have correct column numbers', async ({
+    runner,
+  }) => {
+    const error = await getError(() =>
+      runner.import('/fixtures/esm-external-column-test.js'),
+    )
+    const stack = error.stack!.split('\n')
+    const innerFrame = stack.find((line) => line.includes('inner'))
+    const outerFrame = stack.find((line) => line.includes('outer'))
+
+    // This test verifies the fix for #21561 where ESM external modules had incorrect
+    // column numbers due to an erroneous 62-character offset being subtracted.
+    // The ESM external module has code on a single line with padding:
+    // "var _padding...; export function outer(fn) { return inner(fn); } function inner(fn) { return fn(); }"
+    //
+    // With the bug (subtracting 62), columns would be around 11 and 52.
+    // With the fix (no subtraction), columns should be in a reasonable range (> 60).
+    expect(innerFrame).toBeDefined()
+    expect(outerFrame).toBeDefined()
+
+    // Extract column numbers from stack frames like ":1:114)"
+    const innerMatch = innerFrame!.match(/:(\d+):(\d+)\)/)
+    const outerMatch = outerFrame!.match(/:(\d+):(\d+)\)/)
+
+    expect(innerMatch).toBeDefined()
+    expect(outerMatch).toBeDefined()
+
+    const innerCol = parseInt(innerMatch![2])
+    const outerCol = parseInt(outerMatch![2])
+
+    // Both columns should be > 60 (with the old bug, they would be around 11 and 52)
+    // This verifies the 62-character offset is NOT being incorrectly applied
+    expect(innerCol).toBeGreaterThan(60)
+    expect(outerCol).toBeGreaterThan(60)
+  })
 })

packages/vite/src/node/ssr/runtime/__tests__/utils.ts

@@ -44,7 +44,11 @@ export async function createModuleRunnerTester(
         ws: false,
       },
       ssr: {
-        external: ['@vitejs/cjs-external', '@vitejs/esm-external'],
+        external: [
+          '@vitejs/cjs-external',
+          '@vitejs/esm-external',
+          '@vitejs/esm-external-column-test',
+        ],
       },
       optimizeDeps: {
         disabled: true,