fix: collect coverage using node inspector (fix #378)

packages/vitest/src/coverage.ts

@@ -95,7 +95,6 @@ export interface C8Options {
 }
 
 export interface ResolvedC8Options extends Required<C8Options> {
-  tempDirectory: string
 }
 
 export function resolveC8Options(options: C8Options, root: string): ResolvedC8Options {
@@ -116,17 +115,13 @@ export function resolveC8Options(options: C8Options, root: string): ResolvedC8Op
 
   resolved.reporter = toArray(resolved.reporter)
   resolved.reportsDirectory = resolve(root, resolved.reportsDirectory)
-  resolved.tempDirectory = process.env.NODE_V8_COVERAGE || resolve(resolved.reportsDirectory, 'tmp')
 
   return resolved as ResolvedC8Options
 }
 
 export async function cleanCoverage(options: ResolvedC8Options, clean = true) {
   if (clean && existsSync(options.reportsDirectory))
     await fs.rm(options.reportsDirectory, { recursive: true, force: true })
-
-  if (!existsSync(options.tempDirectory))
-    await fs.mkdir(options.tempDirectory, { recursive: true })
 }
 
 const require = createRequire(import.meta.url)
@@ -136,6 +131,8 @@ export async function reportCoverage(ctx: Vitest) {
   const createReport = require('c8/lib/report')
   const report = createReport(ctx.config.coverage)
 
+  report._loadReports = () => ctx.coverage
+
   const original = report._getMergedProcessCov
 
   report._getMergedProcessCov = () => {

packages/vitest/src/node/cli.ts

@@ -1,5 +1,4 @@
 import cac from 'cac'
-import { execa } from 'execa'
 import type { UserConfig } from '../types'
 import { version } from '../../package.json'
 import { ensurePackageInstalled } from '../utils'
@@ -80,12 +79,6 @@ async function run(cliFilters: string[], options: UserConfig) {
   if (ctx.config.coverage.enabled) {
     if (!await ensurePackageInstalled('c8'))
       process.exit(1)
-
-    if (!process.env.NODE_V8_COVERAGE) {
-      process.env.NODE_V8_COVERAGE = ctx.config.coverage.tempDirectory
-      const { exitCode } = await execa(process.argv0, process.argv.slice(1), { stdio: 'inherit' })
-      process.exit(exitCode)
-    }
   }
 
   if (ctx.config.environment && ctx.config.environment !== 'node') {

packages/vitest/src/node/core.ts

@@ -1,4 +1,5 @@
 import { existsSync } from 'fs'
+import type { Profiler } from 'inspector'
 import type { ViteDevServer } from 'vite'
 import fg from 'fast-glob'
 import mm from 'micromatch'
@@ -24,6 +25,7 @@ export class Vitest {
   server: ViteDevServer = undefined!
   state: StateManager = undefined!
   snapshot: SnapshotManager = undefined!
+  coverage: Profiler.TakePreciseCoverageReturnType[] = []
   reporters: Reporter[] = undefined!
   console: Console
   pool: WorkerPool | undefined
@@ -260,6 +262,7 @@ export class Vitest {
       //   })
       // }
       this.snapshot.clear()
+      this.coverage = []
       const files = Array.from(this.changedTests)
       this.changedTests.clear()
 

packages/vitest/src/node/pool.ts

@@ -111,6 +111,9 @@ function createChannel(ctx: Vitest) {
       snapshotSaved(snapshot) {
         ctx.snapshot.add(snapshot)
       },
+      coverageCollected(coverage) {
+        ctx.coverage.push(coverage)
+      },
       async getSourceMap(id, force) {
         if (force) {
           const mod = ctx.server.moduleGraph.getModuleById(id)

packages/vitest/src/runtime/run.ts

@@ -1,4 +1,5 @@
 import { performance } from 'perf_hooks'
+import inspector from 'inspector'
 import type { HookListener, ResolvedConfig, Suite, SuiteHooks, Task, TaskResult, Test } from '../types'
 import { vi } from '../integrations/vi'
 import { getSnapshotClient } from '../integrations/snapshot/chai'
@@ -188,8 +189,32 @@ export async function startTests(paths: string[], config: ResolvedConfig) {
 
   rpc().onCollected(files)
 
+  let session!: inspector.Session
+  if (config.coverage.enabled) {
+    inspector.open(0)
+    session = new inspector.Session()
+    session.connect()
+
+    session.post('Profiler.enable')
+    session.post('Profiler.startPreciseCoverage', { detailed: true })
+  }
+
   await runSuites(files)
 
+  if (config.coverage.enabled) {
+    session.post('Profiler.takePreciseCoverage', (_, coverage) => {
+      rpc().coverageCollected(coverage)
+    })
+
+    session.disconnect()
+    try {
+      inspector.close()
+    }
+    catch {
+      // Fails inside workers for some reason
+    }
+  }
+
   await getSnapshotClient().saveSnap()
 
   await sendTasksUpdate()

packages/vitest/src/types/worker.ts

@@ -1,3 +1,4 @@
+import type { Profiler } from 'inspector'
 import type { MessagePort } from 'worker_threads'
 import type { FetchFunction, ViteNodeResolveId } from 'vite-node'
 import type { RawSourceMap } from '../types'
@@ -27,4 +28,5 @@ export interface WorkerRPC {
   onTaskUpdate: (pack: TaskResultPack[]) => void
 
   snapshotSaved: (snapshot: SnapshotResult) => void
+  coverageCollected: (coverage: Profiler.TakePreciseCoverageReturnType) => void
 }