fix(frame): fix Frame.waitFor's XPath pattern detection (#5184)

Up to now, only strings starting with '//' are considered as to XPath selectors. Unfortunately, this is too restricting. This fix allows valid XPath selectors starting with: '/', './', and even '(//*[1])'

src/common/FrameManager.ts

@@ -43,6 +43,7 @@ import {
 } from './EvalTypes.js';
 
 const UTILITY_WORLD_NAME = '__puppeteer_utility_world__';
+const xPathPattern = /^\(\/\/[^\)]+\)|^\/\//;
 
 /**
  * We use symbols to prevent external parties listening to these events.
@@ -1068,16 +1069,13 @@ export class Frame {
     options: Record<string, unknown> = {},
     ...args: SerializableOrJSHandle[]
   ): Promise<JSHandle | null> {
-    const xPathPattern = '//';
-
     console.warn(
       'waitFor is deprecated and will be removed in a future release. See https://github.com/puppeteer/puppeteer/issues/6214 for details and how to migrate your code.'
     );
 
     if (helper.isString(selectorOrFunctionOrTimeout)) {
       const string = selectorOrFunctionOrTimeout;
-      if (string.startsWith(xPathPattern))
+      if (xPathPattern.test(string)) return this.waitForXPath(string, options);
-        return this.waitForXPath(string, options);
       return this.waitForSelector(string, options);
     }
     if (helper.isNumber(selectorOrFunctionOrTimeout))

test/waittask.spec.ts

@@ -58,6 +58,18 @@ describe('waittask specs', function () {
       await waitFor;
       expect(found).toBe(true);
     });
+    it('should allow you to select an element with parenthesis-starting xpath', async () => {
+      const { page, server } = getTestState();
+      let found = false;
+      const waitFor = page.waitFor('(//img)[200]').then(() => {
+        found = true;
+      });
+      await page.goto(server.EMPTY_PAGE);
+      expect(found).toBe(false);
+      await page.goto(server.PREFIX + '/grid.html');
+      await waitFor;
+      expect(found).toBe(true);
+    });
     it('should not allow you to select an element with single slash xpath', async () => {
       const { page } = getTestState();