fix(cli): resolve initPage/initScript paths and surface load errors (microsoft#40451)

Author: solomonneas

packages/playwright-core/src/tools/backend/tab.ts

@@ -170,7 +170,8 @@ export class Tab extends EventEmitter<TabEventsInterface> {
         const { default: func } = require(initPage);
         await func({ page: this.page });
       } catch (e) {
-        debug('pw:tools:error')(e);
+        const reason = e instanceof Error ? e.message : String(e);
+        throw new Error(`Failed to load init page "${initPage}": ${reason}`, { cause: e });
       }
     }
   }

packages/playwright-core/src/tools/mcp/config.ts

@@ -115,11 +115,12 @@ export async function resolveCLIConfigForMCP(cliOptions: CLIOptions, env?: NodeJ
   const cliOverrides = configFromCLIOptions(cliOptions);
   const configFile = cliOverrides.configFile ?? envOverrides.configFile;
   const configInFile = await loadConfig(configFile);
+  const configDir = configFile ? path.dirname(path.resolve(configFile)) : process.cwd();
 
   let result = defaultConfig;
-  result = mergeConfig(result, configInFile);
-  result = mergeConfig(result, envOverrides);
-  result = mergeConfig(result, cliOverrides);
+  result = mergeConfig(result, resolveConfigPaths(configInFile, configDir));
+  result = mergeConfig(result, resolveConfigPaths(envOverrides, process.cwd()));
+  result = mergeConfig(result, resolveConfigPaths(cliOverrides, process.cwd()));
 
   const browser = await validateBrowserConfig(result.browser);
   if (browser.launchOptions.headless === undefined)
@@ -151,14 +152,17 @@ export async function resolveCLIConfigForCLI(daemonProfilesDir: string, sessionN
   const envOverrides = configFromEnv(env);
   const configFile = daemonOverrides.configFile ?? envOverrides.configFile;
   const configInFile = await loadConfig(configFile);
+  const configDir = configFile ? path.dirname(path.resolve(configFile)) : process.cwd();
   const globalConfigPath = path.join((env ?? process.env)['PWTEST_CLI_GLOBAL_CONFIG'] ?? os.homedir(), '.playwright', 'cli.config.json');
-  const globalConfigInFile = await loadConfig(fs.existsSync(globalConfigPath) ? globalConfigPath : undefined);
+  const globalConfigExists = fs.existsSync(globalConfigPath);
+  const globalConfigInFile = await loadConfig(globalConfigExists ? globalConfigPath : undefined);
+  const globalConfigDir = globalConfigExists ? path.dirname(globalConfigPath) : process.cwd();
 
   let result = defaultConfig;
-  result = mergeConfig(result, globalConfigInFile);
-  result = mergeConfig(result, configInFile);
-  result = mergeConfig(result, envOverrides);
-  result = mergeConfig(result, daemonOverrides);
+  result = mergeConfig(result, resolveConfigPaths(globalConfigInFile, globalConfigDir));
+  result = mergeConfig(result, resolveConfigPaths(configInFile, configDir));
+  result = mergeConfig(result, resolveConfigPaths(envOverrides, process.cwd()));
+  result = mergeConfig(result, resolveConfigPaths(daemonOverrides, process.cwd()));
 
   if (result.browser.isolated === undefined)
     result.browser.isolated = !options.profile && !options.persistent && !result.browser.userDataDir && !result.browser.remoteEndpoint && !result.browser.cdpEndpoint && !result.extension;
@@ -408,6 +412,18 @@ export async function loadConfig(configFile: string | undefined): Promise<Config
   }
 }
 
+// initPage/initScript paths are resolved against a per-source base dir
+// (config-file dir for entries loaded from a --config file, cwd for entries
+// supplied via CLI flags or PLAYWRIGHT_MCP_INIT_* env vars) so they keep
+// working when the CLI is invoked from a different cwd.
+function resolveConfigPaths(config: Config, baseDir: string): Config {
+  if (config.browser?.initPage)
+    config.browser.initPage = config.browser.initPage.map(p => path.resolve(baseDir, p));
+  if (config.browser?.initScript)
+    config.browser.initScript = config.browser.initScript.map(p => path.resolve(baseDir, p));
+  return config;
+}
+
 function pickDefined<T extends object>(obj: T | undefined): Partial<T> {
   return Object.fromEntries(
       Object.entries(obj ?? {}).filter(([_, v]) => v !== undefined)

tests/mcp/init-page.spec.ts

@@ -15,6 +15,7 @@
  */
 
 import fs from 'fs';
+import path from 'path';
 
 import { test, expect } from './fixtures';
 
@@ -36,6 +37,63 @@ test('--init-page', async ({ startClient }) => {
   });
 });
 
+test('init-page relative path from --config resolves against the config dir', async ({ startClient }) => {
+  // Regression for https://github.com/microsoft/playwright-cli/issues/290:
+  // relative initPage entries in a --config file used to resolve against
+  // cwd (or the require() caller), not the config file's directory. We put
+  // the config + init page in a sibling subdir of cwd so a cwd-based
+  // resolution would miss the file. Same resolution path also covers
+  // browser.initScript.
+  const configDir = test.info().outputPath('cfg');
+  const cwd = test.info().outputPath('cwd');
+  await fs.promises.mkdir(configDir, { recursive: true });
+  await fs.promises.mkdir(cwd, { recursive: true });
+
+  const initPagePath = path.join(configDir, 'initPage.ts');
+  await fs.promises.writeFile(initPagePath, `
+    export default async ({ page }) => {
+      await page.setContent('<div>From relative initPage</div>');
+    };
+  `);
+  const configPath = path.join(configDir, 'config.json');
+  await fs.promises.writeFile(configPath, JSON.stringify({
+    browser: { initPage: ['./initPage.ts'] },
+  }));
+
+  const { client } = await startClient({
+    cwd,
+    args: [`--config=${configPath}`],
+  });
+  expect(await client.callTool({
+    name: 'browser_snapshot',
+    arguments: {},
+  })).toHaveResponse({
+    inlineSnapshot: expect.stringContaining('From relative initPage'),
+  });
+});
+
+test('init-page surfaces load errors instead of silently dropping them', async ({ startClient }) => {
+  // Regression for https://github.com/microsoft/playwright-cli/issues/290:
+  // a failing init-page module used to be swallowed into debug logs, leaving
+  // the user with no signal that their hook never ran.
+  const initPagePath = test.info().outputPath('brokenInitPage.ts');
+  await fs.promises.writeFile(initPagePath, `
+    export default async () => {
+      throw new Error('boom from initPage');
+    };
+  `);
+
+  const { client } = await startClient({
+    args: [`--init-page=${initPagePath}`],
+  });
+  const response: any = await client.callTool({
+    name: 'browser_snapshot',
+    arguments: {},
+  });
+  expect(response.isError).toBe(true);
+  expect(JSON.stringify(response.content)).toContain('boom from initPage');
+});
+
 test('--init-page w/ --init-script', async ({ startClient, server }) => {
   server.setContent('/', `
     <div>Hello world</div>