[Telemetry] Add E2E test for watchdog/shutdown process & fix shutdown logs reliability

Author: ergunsh

src/logger.ts

@@ -31,4 +31,27 @@ export function saveLogsToFile(fileName: string): fs.WriteStream {
   return logFile;
 }
 
+export function saveLogsToFileSync(fileName: string): void {
+
+  debug.enable(namespacesToEnable.join(','));
+
+  let fd: number | undefined;
+  try {
+    fd = fs.openSync(fileName, 'a+');
+  } catch (error: any) {
+    console.error(`Error when opening log file: ${error.message}`);
+    process.exit(1);
+  }
+
+  debug.log = function (...chunks: any[]) {
+    if (fd !== undefined) {
+      try {
+        fs.writeSync(fd, `${chunks.join(' ')}\n`);
+      } catch (e) {
+
+      }
+    }
+  };
+}
+
 export const logger = debug(mcpDebugNamespace);

src/telemetry/watchdog/main.ts

@@ -11,7 +11,7 @@ import readline from 'node:readline';
 import yargs from 'yargs';
 import {hideBin} from 'yargs/helpers';
 
-import {logger, saveLogsToFile} from '../../logger.js';
+import {logger, saveLogsToFileSync} from '../../logger.js';
 import {IpcMessageType, OsType} from '../types.js';
 
 import {ClearcutSender} from './clearcut-sender.js';
@@ -40,18 +40,25 @@ async function main() {
     .parse();
 
   if (argv.logFile) {
-    saveLogsToFile(argv.logFile);
+    saveLogsToFileSync(argv.logFile);
   }
 
-  logger('Watchdog started', {
+  logger('Watchdog started', JSON.stringify({
+    pid: process.pid,
     parentPid: argv.parentPid,
     version: argv.appVersion,
     osType: argv.osType,
-  });
+  }, null, 2));
 
   const sender = new ClearcutSender(argv.appVersion, argv.osType as OsType);
 
+  let isShuttingDown = false;
   function onParentDeath(reason: string) {
+    if (isShuttingDown) {
+      return;
+    }
+
+    isShuttingDown = true;
     logger(`Parent death detected (${reason}). Sending shutdown event...`);
     sender
       .sendShutdownEvent()

tests/e2e/telemetry.test.ts

@@ -0,0 +1,107 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import {describe, it} from 'node:test';
+import assert from 'node:assert';
+import {spawn} from 'node:child_process';
+import fs from 'node:fs';
+import path from 'node:path';
+import os from 'node:os';
+
+describe('Telemetry E2E', () => {
+  it('spawns server, logs events, and shuts down watchdog cleanly on termination', async () => {
+    // Setup
+    const logFile = path.join(os.tmpdir(), `test-mcp-telemetry-${Date.now()}.log`);
+    const serverPath = path.resolve('build/src/main.js');
+
+    if (!fs.existsSync(serverPath)) {
+        throw new Error(`Server build not found at ${serverPath}. Run 'npm run build' first.`);
+    }
+
+    // Spawn Server
+    console.log(`Spawning server at ${serverPath} with log file ${logFile}`);
+    const server = spawn(process.execPath, [
+      serverPath,
+      `--log-file=${logFile}`,
+      '--usage-statistics',
+      '--headless',
+      '--app-version=1.0.0'
+    ], {
+      stdio: ['pipe', 'pipe', 'pipe'],
+    });
+
+    server.stderr.on('data', (d) => console.log(`Stderr: ${d}`));
+
+    // Wait for Watchdog start
+    let watchdogPid: number | undefined;
+    const waitForWatchdogStart = new Promise<void>((resolve, reject) => {
+      const checkInterval = setInterval(() => {
+        if (server.exitCode !== null) {
+          clearInterval(checkInterval);
+          reject(new Error(`Server exited early with code ${server.exitCode}`));
+          return;
+        }
+
+        if (fs.existsSync(logFile)) {
+          const content = fs.readFileSync(logFile, 'utf8');
+          const match = content.match(/Watchdog started[\s\S]*?"pid":\s*(\d+)/);
+          if (match) {
+            watchdogPid = parseInt(match[1]);
+            clearInterval(checkInterval);
+            resolve();
+          }
+        }
+      }, 100);
+      setTimeout(() => {
+        clearInterval(checkInterval);
+        reject(new Error('Timeout waiting for Watchdog start'));
+      }, 5000);
+    });
+
+    await waitForWatchdogStart;
+    assert.ok(watchdogPid, 'Watchdog PID not found');
+    console.log(`Watchdog started with PID ${watchdogPid}`);
+
+    // Verify start event logged
+    const contentBeforeKill = fs.readFileSync(logFile, 'utf8');
+    assert.match(contentBeforeKill, /server_start/);
+
+    // Kill Server with SIGKILL
+    console.log(`Killing server process ${server.pid} with SIGKILL`);
+    server.kill('SIGKILL');
+
+    // Wait for Watchdog exit
+    const waitForWatchdogExit = new Promise<void>((resolve, reject) => {
+      const checkInterval = setInterval(() => {
+        try {
+          process.kill(watchdogPid!, 0); // Check if running
+        } catch (e) {
+          clearInterval(checkInterval);
+          resolve();
+          return;
+        }
+      }, 100);
+      
+      setTimeout(() => {
+        clearInterval(checkInterval);
+        try { process.kill(watchdogPid!, 'SIGKILL'); } catch {}
+        reject(new Error('Timeout waiting for Watchdog exit'));
+      }, 5000);
+    });
+
+    await waitForWatchdogExit;
+    console.log('Watchdog process is gone');
+
+    // Verify shutdown logged
+    const contentAfter = fs.readFileSync(logFile, 'utf8');
+    assert.match(contentAfter, /Parent death detected/);
+    assert.match(contentAfter, /server_shutdown/);
+    console.log('Shutdown events verified');
+
+    // Cleanup
+    if (fs.existsSync(logFile)) fs.unlinkSync(logFile);
+  });
+});