fix: --inspect-brk to pause before execution

packages/vite-node/src/source-map.ts

@@ -48,6 +48,11 @@ export function withInlineSourcemap(result: TransformResult, options: {
   while (OTHER_SOURCE_MAP_REGEXP.test(code))
     code = code.replace(OTHER_SOURCE_MAP_REGEXP, '')
 
+  // If the first line is not present on source maps, add simple 1:1 mapping ([0,0,0,0], [1,0,0,0])
+  // so that debuggers can be set to break on first line
+  if (map.mappings.startsWith(';'))
+    map.mappings = `AAAA,CAAA${map.mappings}`
+
   const sourceMap = Buffer.from(JSON.stringify(map), 'utf-8').toString('base64')
   result.code = `${code.trimEnd()}\n\n${VITE_NODE_SOURCEMAPPING_SOURCE}\n//# ${VITE_NODE_SOURCEMAPPING_URL};base64,${sourceMap}\n`
 

packages/vitest/src/runtime/inspector.ts

@@ -1,15 +1,17 @@
 import { createRequire } from 'node:module'
 
-import type { ResolvedConfig } from '../types'
+import type { ContextRPC } from '../types'
 
 const __require = createRequire(import.meta.url)
 let inspector: typeof import('node:inspector')
+let session: InstanceType<typeof inspector.Session>
 
 /**
  * Enables debugging inside `worker_threads` and `child_process`.
  * Should be called as early as possible when worker/process has been set up.
  */
-export function setupInspect(config: ResolvedConfig) {
+export function setupInspect(ctx: ContextRPC) {
+  const config = ctx.config
   const isEnabled = config.inspect || config.inspectBrk
 
   if (isEnabled) {
@@ -20,8 +22,22 @@ export function setupInspect(config: ResolvedConfig) {
     if (!isOpen) {
       inspector.open()
 
-      if (config.inspectBrk)
+      if (config.inspectBrk) {
         inspector.waitForDebugger()
+        const firstTestFile = ctx.files[0]
+
+        // Stop at first test file
+        if (firstTestFile) {
+          session = new inspector.Session()
+          session.connect()
+
+          session.post('Debugger.enable')
+          session.post('Debugger.setBreakpointByUrl', {
+            lineNumber: 0,
+            url: new URL(firstTestFile, import.meta.url).href,
+          })
+        }
+      }
     }
   }
 
@@ -32,7 +48,9 @@ export function setupInspect(config: ResolvedConfig) {
   const keepOpen = config.watch && (isIsolatedSingleFork || isIsolatedSingleThread)
 
   return function cleanup() {
-    if (isEnabled && !keepOpen && inspector)
+    if (isEnabled && !keepOpen && inspector) {
       inspector.close()
+      session?.disconnect()
+    }
   }
 }

packages/vitest/src/runtime/worker.ts

@@ -15,7 +15,7 @@ if (isChildProcess())
 export async function run(ctx: ContextRPC) {
   const prepareStart = performance.now()
 
-  const inspectorCleanup = setupInspect(ctx.config)
+  const inspectorCleanup = setupInspect(ctx)
 
   process.env.VITEST_WORKER_ID = String(ctx.workerId)
   process.env.VITEST_POOL_ID = String(poolId)

test/inspect/fixtures/math.test.ts

@@ -0,0 +1,5 @@
+import { expect, test } from "vitest";
+
+test("sum", () => {
+  expect(1 + 1).toBe(2)
+})

test/inspect/fixtures/vitest.config.ts

@@ -0,0 +1,8 @@
+import { defineConfig } from 'vitest/config'
+
+export default defineConfig({
+  test: {
+    include: ['./**.test.ts'],
+    watch: false,
+  },
+})

test/inspect/package.json

@@ -0,0 +1,13 @@
+{
+  "name": "@vitest/test-inspect",
+  "type": "module",
+  "private": true,
+  "scripts": {
+    "test": "vitest"
+  },
+  "devDependencies": {
+    "vite": "latest",
+    "vitest": "workspace:*",
+    "ws": "^8.14.2"
+  }
+}

test/inspect/test/inspect.test.ts

@@ -0,0 +1,86 @@
+import type { InspectorNotification } from 'node:inspector'
+import { expect, test } from 'vitest'
+import WebSocket from 'ws'
+
+import { isWindows } from '../../../packages/vite-node/src/utils'
+import { runVitestCli } from '../../test-utils'
+
+type Message = Partial<InspectorNotification<any>>
+
+test.skipIf(isWindows)('--inspect-brk stops at test file', async () => {
+  const vitest = await runVitestCli('--root', 'fixtures', '--inspect-brk', '--no-file-parallelism')
+
+  await vitest.waitForStderr('Debugger listening on ')
+  const url = vitest.stderr.split('\n')[0].replace('Debugger listening on ', '')
+
+  const { receive, send } = await createChannel(url)
+
+  send({ method: 'Debugger.enable' })
+  send({ method: 'Runtime.enable' })
+  await receive('Runtime.executionContextCreated')
+
+  const paused = receive('Debugger.paused')
+  send({ method: 'Runtime.runIfWaitingForDebugger' })
+
+  const { params } = await paused
+  const scriptId = params.callFrames[0].functionLocation.scriptId
+
+  // Verify that debugger paused on test file
+  const response = receive()
+  send({ method: 'Debugger.getScriptSource', params: { scriptId } })
+  const { result } = await response as any
+
+  expect(result.scriptSource).toContain('test("sum", () => {')
+  expect(result.scriptSource).toContain('expect(1 + 1).toBe(2)')
+
+  send({ method: 'Debugger.resume' })
+
+  await vitest.waitForStdout('Test Files  1 passed (1)')
+  await vitest.isDone
+})
+
+async function createChannel(url: string) {
+  const ws = new WebSocket(url)
+
+  let id = 1
+  let receiver = defer()
+
+  ws.onerror = receiver.reject
+  ws.onmessage = (message) => {
+    const response = JSON.parse(message.data.toString())
+    receiver.resolve(response)
+  }
+
+  async function receive(filter?: string) {
+    const message = await receiver.promise
+    receiver = defer()
+
+    if (filter && message.method !== filter)
+      return receive(filter)
+
+    return message
+  }
+
+  function send(message: Message) {
+    ws.send(JSON.stringify({ ...message, id: id++ }))
+  }
+
+  await new Promise(r => ws.on('open', r))
+
+  return { receive, send }
+}
+
+function defer(): {
+  promise: Promise<Message>
+  resolve: (response: Message) => void
+  reject: (error: unknown) => void
+} {
+  const pr = {} as ReturnType<typeof defer>
+
+  pr.promise = new Promise((resolve, reject) => {
+    pr.resolve = resolve
+    pr.reject = reject
+  })
+
+  return pr
+}

test/inspect/vitest.config.ts

@@ -0,0 +1,7 @@
+import { defineConfig } from 'vitest/config'
+
+export default defineConfig({
+  test: {
+    include: ['./test/**'],
+  },
+})

test/test-utils/index.ts

@@ -188,6 +188,9 @@ export async function runCli(command: string, _options?: Options | string, ...ar
     await cli.isDone
   })
 
+  if (args.includes('--inspect') || args.includes('--inspect-brk'))
+    return cli
+
   if (args.includes('--watch')) {
     if (command === 'vitest') // Wait for initial test run to complete
       await cli.waitForStdout('Waiting for file changes')