test: init e2e (#34193)

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

e2e/support/web-server.ts

@@ -0,0 +1,83 @@
+import type { ManagedProcess } from './process'
+import { isPortReachable, startLoggedProcess, stopManagedProcess, waitForUrl } from './process'
+
+type WebServerStartOptions = {
+  baseURL: string
+  command: string
+  args?: string[]
+  cwd: string
+  logFilePath: string
+  reuseExistingServer: boolean
+  timeoutMs: number
+}
+
+let activeProcess: ManagedProcess | undefined
+
+const getUrlHostAndPort = (url: string) => {
+  const parsedUrl = new URL(url)
+  const isHttps = parsedUrl.protocol === 'https:'
+
+  return {
+    host: parsedUrl.hostname,
+    port: parsedUrl.port ? Number(parsedUrl.port) : isHttps ? 443 : 80,
+  }
+}
+
+export const startWebServer = async ({
+  baseURL,
+  command,
+  args = [],
+  cwd,
+  logFilePath,
+  reuseExistingServer,
+  timeoutMs,
+}: WebServerStartOptions) => {
+  const { host, port } = getUrlHostAndPort(baseURL)
+
+  if (reuseExistingServer && (await isPortReachable(host, port))) return
+
+  activeProcess = await startLoggedProcess({
+    command,
+    args,
+    cwd,
+    label: 'web server',
+    logFilePath,
+  })
+
+  let startupError: Error | undefined
+  activeProcess.childProcess.once('error', (error) => {
+    startupError = error
+  })
+  activeProcess.childProcess.once('exit', (code, signal) => {
+    if (startupError) return
+
+    startupError = new Error(
+      `Web server exited before readiness (code: ${code ?? 'unknown'}, signal: ${signal ?? 'none'}).`,
+    )
+  })
+
+  const deadline = Date.now() + timeoutMs
+  while (Date.now() < deadline) {
+    if (startupError) {
+      await stopManagedProcess(activeProcess)
+      activeProcess = undefined
+      throw startupError
+    }
+
+    try {
+      await waitForUrl(baseURL, 1_000, 250, 1_000)
+      return
+    } catch {
+      // Continue polling until timeout or child exit.
+    }
+  }
+
+  await stopManagedProcess(activeProcess)
+  activeProcess = undefined
+  throw new Error(`Timed out waiting for web server readiness at ${baseURL} after ${timeoutMs}ms.`)
+}
+
+export const stopWebServer = async () => {
+  await stopManagedProcess(activeProcess)
+  activeProcess = undefined
+}