Continue work on WTR

1. ✅ Fixture routing via middleware
2. ✅ Sauce region configurability via SAUCE_REGION env var
3. ✅ Firefox moz:debuggerAddress: true capability

Author: flavorjones

web-test-runner.config.mjs

@@ -1,8 +1,19 @@
 import { playwrightLauncher } from '@web/test-runner-playwright';
+import path from 'path';
+import fs from 'fs';
+
+// Map SAUCE_REGION env var to hostname
+const sauceRegionHostnames = {
+  'us': 'ondemand.us-west-1.saucelabs.com',
+  'us-west-1': 'ondemand.us-west-1.saucelabs.com',
+  'us-east-4': 'ondemand.us-east-4.saucelabs.com',
+  'eu': 'ondemand.eu-central-1.saucelabs.com',
+  'eu-central-1': 'ondemand.eu-central-1.saucelabs.com',
+};
 
 // Build SauceLabs launchers if credentials are available
 const sauceLabsConfig = process.env.SAUCE_ACCESS_KEY ? {
-  hostname: 'ondemand.us-west-1.saucelabs.com',
+  hostname: sauceRegionHostnames[process.env.SAUCE_REGION] || 'ondemand.us-west-1.saucelabs.com',
   port: 443,
   path: '/wd/hub',
   protocol: 'https',
@@ -44,6 +55,7 @@ const createSauceLabsLaunchers = async () => {
         browserName: 'firefox',
         browserVersion: 'latest',
         platformName: 'Windows 10',
+        'moz:debuggerAddress': true,  // Required for SauceLabs Firefox
         'sauce:options': sauceOptions,
       },
     }),
@@ -85,6 +97,23 @@ export default {
   // Parallel browser execution
   concurrency: sauceLabsConfig ? 4 : 1,
 
+  // Middleware to serve test fixtures from src/test/test_helpers/fixtures/
+  middleware: [
+    function serveFixtures(context, next) {
+      if (context.url.startsWith('/test_helpers/fixtures/')) {
+        const filePath = path.join(process.cwd(), 'src/test', context.url);
+        if (fs.existsSync(filePath)) {
+          context.body = fs.createReadStream(filePath);
+          const ext = path.extname(filePath).toLowerCase();
+          const mimeTypes = { '.png': 'image/png', '.jpg': 'image/jpeg', '.gif': 'image/gif' };
+          context.type = mimeTypes[ext] || 'application/octet-stream';
+          return;
+        }
+      }
+      return next();
+    },
+  ],
+
   // Custom HTML that sets up QUnit and bridges to WTR
   // Note: first param is testFrameworkImport (mocha path by default), which we ignore
   // We use getConfig() to get the actual test file path