From de5af2939099c448ba179341debf7d376fd9fdc5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ari=20Perkki=C3=B6?= <ari.perkkio@gmail.com>
Date: Sun, 18 Oct 2026 16:27:45 +0300
Subject: [PATCH] fix(coverage): v8 `autoAttachSubprocess` to use `.tmp`
 directory (#11632)

---
 packages/coverage-v8/src/index.ts             |  2 +-
 .../test/temporary-files.test.ts              | 28 +++++++++++++++++--
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/packages/coverage-v8/src/index.ts b/packages/coverage-v8/src/index.ts
index 962e18e63..f37440da8 100644
--- a/packages/coverage-v8/src/index.ts
+++ b/packages/coverage-v8/src/index.ts
@@ -31,7 +31,7 @@ const mod: CoverageProviderModule & {
     enabled = true
 
     if (autoAttachSubprocess) {
-      this.extendedContextCoverageDir = resolve(reportsDirectory, 'tmp', randomUUID())
+      this.extendedContextCoverageDir = resolve(reportsDirectory, '.tmp', randomUUID())
       process.env.NODE_V8_COVERAGE = this.extendedContextCoverageDir
     }
 
diff --git a/test/coverage-test/test/temporary-files.test.ts b/test/coverage-test/test/temporary-files.test.ts
index b2264458e..fd527b2b2 100644
--- a/test/coverage-test/test/temporary-files.test.ts
+++ b/test/coverage-test/test/temporary-files.test.ts
@@ -1,7 +1,7 @@
 import { readdirSync } from 'node:fs'
 import { resolve } from 'node:path'
 import { expect } from 'vitest'
-import { runVitest, test } from '../utils'
+import { isBrowser, isV8Provider, runVitest, test } from '../utils'
 
 test('temporary files are removed after test', async () => {
   await runVitest({
@@ -12,9 +12,31 @@ test('temporary files are removed after test', async () => {
   const coveragePath = resolve('./coverage')
   const files = readdirSync(coveragePath)
 
-  expect(files).not.toContain('.tmp')
+  expect.soft(files).not.toContain('.tmp')
 
-  expect(files).toMatchInlineSnapshot(`
+  expect.soft(files).toMatchInlineSnapshot(`
+    [
+      "coverage-final.json",
+    ]
+  `)
+})
+
+test('temporary files from autoAttachSubprocess are removed after test', async ({ skip }) => {
+  skip(!isV8Provider() || isBrowser(), 'V8 + node only feature')
+
+  await runVitest({
+    include: ['fixtures/test/child-process.test.ts'],
+    pool: 'forks',
+    coverage: { reporter: 'json', autoAttachSubprocess: true },
+  })
+
+  const coveragePath = resolve('./coverage')
+  const files = readdirSync(coveragePath)
+
+  expect.soft(files).not.toContain('.tmp')
+  expect.soft(files).not.toContain('tmp')
+
+  expect.soft(files).toMatchInlineSnapshot(`
     [
       "coverage-final.json",
     ]
-- 
2.54.0