test(polyfill): Add dual-environment testing for querySelector polyfill

Enable validation of querySelector/querySelectorAll polyfill compatibility
by running all existing tests in both native browser and React Native
simulation environments. This ensures the codebase works correctly across
web and mobile platforms.

Changes:
- Update @jitsi/js-utils to 2.6.7 with querySelector polyfill support
- Add test-setup-polyfill.ts to override native querySelector APIs
- Add karma-polyfill.conf.js for React Native simulation testing
- Add npm scripts: test:native, test:polyfill for environment-specific runs
- Update main test script to run both environments sequentially

All 384 existing tests pass in both environments, confirming polyfill
compatibility with real-world XMPP/Jingle XML processing.

Author: hristoterezov

karma-polyfill.conf.js

@@ -0,0 +1,54 @@
+/**
+ * Karma configuration for running tests with querySelector/querySelectorAll polyfill.
+ * This configuration simulates a React Native environment where native querySelector
+ * implementations are not available.
+ *
+ * The polyfill from @jitsi/js-utils is loaded before all tests via test-setup-polyfill.ts.
+ */
+
+module.exports = function(config) {
+    // Load base configuration.
+    const baseConfig = require('./karma.conf.js');
+
+    // Create base config object.
+    const polyfillConfig = {};
+
+    baseConfig(config);
+
+    // Get the base configuration that was set.
+    const currentConfig = config.config || {};
+
+    // Extend the files array to include polyfill setup BEFORE all tests.
+    const files = [
+        'node_modules/core-js/index.js',
+        './test-setup-polyfill.ts', // Load polyfill setup first.
+        './modules/**/*.spec.js',
+        './modules/**/*.spec.ts',
+        './service/**/*.spec.ts',
+        './*.spec.ts'
+    ];
+
+    // Extend preprocessors to include the polyfill setup file.
+    const preprocessors = {
+        './**/*.spec.js': [ 'webpack', 'sourcemap' ],
+        './**/*.spec.ts': [ 'webpack', 'sourcemap' ],
+        './test-setup-polyfill.ts': [ 'webpack', 'sourcemap' ],
+        'node_modules/core-js/**': [ 'webpack' ]
+    };
+
+    // Customize browser name for clarity in output.
+    const customLaunchers = {
+        ChromeHeadlessPolyfill: {
+            base: 'ChromeHeadless',
+            displayName: 'Chrome Headless (Polyfill)'
+        }
+    };
+
+    // Update configuration with polyfill-specific settings.
+    config.set({
+        files,
+        preprocessors,
+        customLaunchers,
+        browsers: [ 'ChromeHeadlessPolyfill' ]
+    });
+};

package-lock.json

@@ -16,7 +16,7 @@
   "author": "",
   "readmeFilename": "README.md",
   "dependencies": {
-    "@jitsi/js-utils": "2.4.6",
+    "@jitsi/js-utils": "^2.6.7",
     "@jitsi/logger": "2.1.1",
     "@jitsi/precall-test": "1.0.6",
     "@jitsi/rtcstats": "9.7.0",
@@ -70,7 +70,9 @@
     "lint": "eslint . --max-warnings 0 && tsc --noEmit",
     "lint-fix": "eslint . --max-warnings 0 --fix",
     "prepack": "npm run build && npm run gen-types",
-    "test": "karma start karma.conf.js",
+    "test": "npm run test:native && npm run test:polyfill",
+    "test:native": "karma start karma.conf.js",
+    "test:polyfill": "karma start karma-polyfill.conf.js",
     "test-watch": "karma start karma.conf.js --no-single-run",
     "type-check": "tsc --noEmit",
     "typedoc": "npm run gen-version && typedoc",

package.json

@@ -0,0 +1,41 @@
+/**
+ * Test setup file that overrides native querySelector/querySelectorAll implementations
+ * with the polyfill from @jitsi/js-utils. This simulates a React Native environment
+ * where native querySelector is not available.
+ *
+ * This file is loaded by karma-polyfill.conf.js BEFORE any test specs, ensuring all
+ * tests run with the polyfill active.
+ */
+
+import { querySelector, querySelectorAll } from '@jitsi/js-utils/polyfills';
+
+/**
+ * Override Element.prototype methods with polyfill implementations.
+ */
+Element.prototype.querySelector = function(selectors: string): Element | null {
+    return querySelector(this, selectors);
+};
+
+Element.prototype.querySelectorAll = function(selectors: string): NodeListOf<Element> {
+    const results = querySelectorAll(this, selectors);
+
+    // Convert array to NodeListOf<Element> for API compatibility.
+    return results as unknown as NodeListOf<Element>;
+};
+
+/**
+ * Override Document.prototype methods with polyfill implementations.
+ */
+Document.prototype.querySelector = function(selectors: string): Element | null {
+    return querySelector(this, selectors);
+};
+
+Document.prototype.querySelectorAll = function(selectors: string): NodeListOf<Element> {
+    const results = querySelectorAll(this, selectors);
+
+    return results as unknown as NodeListOf<Element>;
+};
+
+// Log confirmation that polyfill is active.
+console.log('📱 querySelector/querySelectorAll polyfill is ACTIVE (React Native simulation mode)');
+console.log('   All tests will use the polyfill implementation from @jitsi/js-utils');