[ide-mode] Write port to file in ide-server (#5811)

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

integration-tests/ide-client.test.ts

@@ -0,0 +1,139 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import * as fs from 'node:fs';
+import * as os from 'node:os';
+import * as path from 'node:path';
+import * as net from 'node:net';
+import { IdeClient } from '../packages/core/src/ide/ide-client.js';
+import { getIdeProcessId } from '../packages/core/src/ide/process-utils.js';
+import { spawn, ChildProcess } from 'child_process';
+
+describe('IdeClient', () => {
+  it('reads port from file and connects', async () => {
+    const port = 12345;
+    const pid = await getIdeProcessId();
+    const portFile = path.join(os.tmpdir(), `gemini-ide-server-${pid}.json`);
+    fs.writeFileSync(portFile, JSON.stringify({ port }));
+
+    const ideClient = IdeClient.getInstance();
+    await ideClient.connect();
+
+    expect(ideClient.getConnectionStatus().status).not.toBe('disconnected');
+
+    fs.unlinkSync(portFile);
+  });
+});
+
+const getFreePort = (): Promise<number> => {
+  return new Promise((resolve, reject) => {
+    const server = net.createServer();
+    server.unref();
+    server.on('error', reject);
+    server.listen(0, () => {
+      const port = (server.address() as net.AddressInfo).port;
+      server.close(() => {
+        resolve(port);
+      });
+    });
+  });
+};
+
+describe('IdeClient fallback connection logic', () => {
+  let server: net.Server;
+  let envPort: number;
+  let pid: number;
+  let portFile: string;
+
+  beforeEach(async () => {
+    pid = await getIdeProcessId();
+    portFile = path.join(os.tmpdir(), `gemini-ide-server-${pid}.json`);
+    envPort = await getFreePort();
+    server = net.createServer().listen(envPort);
+    process.env['GEMINI_CLI_IDE_SERVER_PORT'] = String(envPort);
+    process.env['GEMINI_CLI_IDE_WORKSPACE_PATH'] = process.cwd();
+    // Reset instance
+    IdeClient.instance = undefined;
+  });
+
+  afterEach(() => {
+    server.close();
+    delete process.env['GEMINI_CLI_IDE_SERVER_PORT'];
+    delete process.env['GEMINI_CLI_IDE_WORKSPACE_PATH'];
+    if (fs.existsSync(portFile)) {
+      fs.unlinkSync(portFile);
+    }
+  });
+
+  it('connects using env var when port file does not exist', async () => {
+    // Ensure port file doesn't exist
+    if (fs.existsSync(portFile)) {
+      fs.unlinkSync(portFile);
+    }
+
+    const ideClient = IdeClient.getInstance();
+    await ideClient.connect();
+
+    expect(ideClient.getConnectionStatus().status).toBe('connected');
+  });
+
+  it('falls back to env var when connection with port from file fails', async () => {
+    const filePort = await getFreePort();
+    // Write port file with a port that is not listening
+    fs.writeFileSync(portFile, JSON.stringify({ port: filePort }));
+
+    const ideClient = IdeClient.getInstance();
+    await ideClient.connect();
+
+    expect(ideClient.getConnectionStatus().status).toBe('connected');
+  });
+});
+
+describe('getIdeProcessId', () => {
+  let child: ChildProcess;
+
+  afterEach(() => {
+    if (child) {
+      child.kill();
+    }
+  });
+
+  it('should return the pid of the parent process', async () => {
+    // We need to spawn a child process that will run the test
+    // so that we can check that getIdeProcessId returns the pid of the parent
+    const parentPid = process.pid;
+    const output = await new Promise<string>((resolve, reject) => {
+      child = spawn(
+        'node',
+        [
+          '-e',
+          `
+        const { getIdeProcessId } = require('../packages/core/src/ide/process-utils.js');
+        getIdeProcessId().then(pid => console.log(pid));
+      `,
+        ],
+        {
+          stdio: ['pipe', 'pipe', 'pipe'],
+        },
+      );
+
+      let out = '';
+      child.stdout?.on('data', (data) => {
+        out += data.toString();
+      });
+
+      child.on('close', (code) => {
+        if (code === 0) {
+          resolve(out.trim());
+        } else {
+          reject(new Error(`Child process exited with code ${code}`));
+        }
+      });
+    });
+
+    expect(parseInt(output, 10)).toBe(parentPid);
+  }, 10000);
+});