From 87c9a56d0f0bd2e964e5ae3faf1ad389089ae74e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ari=20Perkki=C3=B6?= <ari.perkkio@gmail.com>
Date: Mon, 9 Dec 2024 10:40:12 +0200
Subject: [PATCH] fix(coverage): `isolate: false` with browser mode

---
 packages/coverage-v8/src/browser.ts           | 15 +++++++++++----
 test/coverage-test/test/isolation.test.ts     |  8 +++++++-
 test/coverage-test/utils.ts                   |  1 +
 test/coverage-test/vitest.workspace.custom.ts |  2 ++
 4 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/packages/coverage-v8/src/browser.ts b/packages/coverage-v8/src/browser.ts
index 3f3940892129..3ae9f51f463a 100644
--- a/packages/coverage-v8/src/browser.ts
+++ b/packages/coverage-v8/src/browser.ts
@@ -1,13 +1,21 @@
+import type { CoverageProviderModule } from 'vitest/node'
 import type { V8CoverageProvider } from './provider'
 import { cdp } from '@vitest/browser/context'
 import { loadProvider } from './load-provider'
 
 const session = cdp()
+let enabled = false
 
 type ScriptCoverage = Awaited<ReturnType<typeof session.send<'Profiler.takePreciseCoverage'>>>
 
-export default {
+export default <CoverageProviderModule>{
   async startCoverage() {
+    if (enabled) {
+      return
+    }
+
+    enabled = true
+
     await session.send('Profiler.enable')
     await session.send('Profiler.startPreciseCoverage', {
       callCount: true,
@@ -32,9 +40,8 @@ export default {
     return { result }
   },
 
-  async stopCoverage() {
-    await session.send('Profiler.stopPreciseCoverage')
-    await session.send('Profiler.disable')
+  stopCoverage() {
+    // Browser mode should not stop coverage as same V8 instance is shared between tests
   },
 
   async getProvider(): Promise<V8CoverageProvider> {
diff --git a/test/coverage-test/test/isolation.test.ts b/test/coverage-test/test/isolation.test.ts
index 9d32038fecb3..02414bf6008b 100644
--- a/test/coverage-test/test/isolation.test.ts
+++ b/test/coverage-test/test/isolation.test.ts
@@ -14,7 +14,12 @@ for (const isolate of [true, false]) {
 
       coverage: {
         all: false,
-        reporter: 'json',
+        reporter: ['json', 'html'],
+      },
+
+      // @ts-expect-error -- merged in runVitest
+      browser: {
+        isolate,
       },
     })
 
@@ -33,6 +38,7 @@ for (const isolate of [true, false]) {
     expect(math.toSummary().branches.pct).toBe(100)
   })
 }
+
 class Sorter {
   sort(files: WorkspaceSpec[]) {
     return files.sort((a) => {
diff --git a/test/coverage-test/utils.ts b/test/coverage-test/utils.ts
index 5efe5731bd07..0486120b93fa 100644
--- a/test/coverage-test/utils.ts
+++ b/test/coverage-test/utils.ts
@@ -51,6 +51,7 @@ export async function runVitest(config: UserConfig, options = { throwOnError: tr
       headless: true,
       name: 'chromium',
       provider: 'playwright',
+      ...config.browser,
     },
   })
 
diff --git a/test/coverage-test/vitest.workspace.custom.ts b/test/coverage-test/vitest.workspace.custom.ts
index 6974b93ca907..361bce3f3414 100644
--- a/test/coverage-test/vitest.workspace.custom.ts
+++ b/test/coverage-test/vitest.workspace.custom.ts
@@ -66,6 +66,7 @@ export default defineWorkspace([
         BROWSER_TESTS,
 
         // Other non-provider-specific tests that should be run on browser mode as well
+        '**/isolation.test.ts',
         '**/include-exclude.test.ts',
         '**/allow-external.test.ts',
         '**/ignore-hints.test.ts',
@@ -90,6 +91,7 @@ export default defineWorkspace([
         BROWSER_TESTS,
 
         // Other non-provider-specific tests that should be run on browser mode as well
+        '**/isolation.test.ts',
         '**/include-exclude.test.ts',
         '**/allow-external.test.ts',
         '**/ignore-hints.test.ts',