cherry-pick(#27188): fix(locators): do not escape regular expressions with u or v flag (#27190)

Fixes #27163.

Author: dgozman

packages/playwright-core/src/utils/isomorphic/stringUtils.ts

@@ -74,6 +74,12 @@ export function normalizeEscapedRegexQuotes(source: string) {
 }
 
 function escapeRegexForSelector(re: RegExp): string {
+  // Unicode mode does not allow "identity character escapes", so we do not escape and
+  // hope that it does not contain quotes and/or >> signs.
+  // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Regular_expressions/Character_escape
+  // TODO: rework RE usages in internal selectors away from literal representation to json, e.g. {source,flags}.
+  if (re.unicode || (re as any).unicodeSets)
+    return String(re);
   // Even number of backslashes followed by the quote -> insert a backslash.
   return String(re).replace(/(^|[^\\])(\\\\)*(["'`])/g, '$1$2\\$3').replace(/>>/g, '\\>\\>');
 }

tests/page/locator-query.spec.ts

@@ -115,6 +115,10 @@ it('should filter by regex with a single quote', async ({ page }) => {
   await expect.soft(page.getByRole('button', { name: /let\\'s let\\\'s/i }).locator('span')).toHaveText('hello');
   await expect.soft(page.locator('button', { hasText: /let\\\'s let\\'s/i }).locator('span')).toHaveText('hello');
   await expect.soft(page.getByRole('button', { name: /let\\\'s let\\'s/i }).locator('span')).toHaveText('hello');
+
+  await page.setContent(`<button>let's hello</button>`);
+  await expect.soft(page.locator('button', { hasText: /let's/iu })).toHaveText(`let's hello`);
+  await expect.soft(page.getByRole('button', { name: /let's/iu })).toHaveText(`let's hello`);
 });
 
 it('should filter by regex and regexp flags', async ({ page }) => {