build: switch to macos "large" to fix missing Firefox

The Arm64 images have been catered to Google and its Chrome browser
only, omitting Firefox.

Ref actions/runner-images#9974

.github/workflows/CI.yaml

@@ -27,9 +27,9 @@ jobs:
             node: 20.x
 
           # Includes Firefox, Google Chrome, Safari
-          # https://github.com/actions/runner-images/blob/macos-15/20241217.493/images/macos/macos-15-Readme.md
+          # https://github.com/actions/runner-images/blob/macos-13/20241216.479/images/macos/macos-13-Readme.md
           - name: "macOS: Node 20"
-            os: macos-15
+            os: macos-13
             node: 20.x
 
     name: ${{ matrix.name }}

src/browsers.js

@@ -33,15 +33,16 @@ class LocalBrowser {
     let exe;
     for (const candidate of candidates) {
       if (candidate !== null) {
-        logger.debug('browser_exe_check', candidate);
         // Optimization: Use fs.existsSync. It is on par with accessSync and statSync,
         // and beats concurrent fs/promises.access(cb) via Promise.all().
         // Starting the promise chain alone takes the same time as a loop with
         // 5x existsSync(), not even counting the await and boilerplate to manage it all.
         if (fs.existsSync(candidate)) {
-          logger.debug('browser_exe_found');
+          logger.debug('browser_exe_found', candidate);
           exe = candidate;
           break;
+        } else {
+          logger.debug('browser_exe_check', candidate);
         }
       }
     }
@@ -162,7 +163,7 @@ class LocalBrowser {
 }
 
 class FirefoxBrowser {
-  * getCandidates () {
+  static * #getCandidates () {
     if (process.env.FIREFOX_BIN) yield process.env.FIREFOX_BIN;
 
     // Find /usr/bin/firefox on platforms like linux (including WSL), freebsd, openbsd.
@@ -183,7 +184,7 @@ class FirefoxBrowser {
     // if (LocalBrowser.isWsl()) { }
   }
 
-  static createPrefsJs (prefs) {
+  static #createPrefsJs (prefs) {
     let js = '';
     for (const key in prefs) {
       js += 'user_pref("' + key + '", ' + JSON.stringify(prefs[key]) + ');\n';
@@ -203,7 +204,7 @@ class FirefoxBrowser {
     // https://github.com/airtap/the-last-browser-launcher/blob/v0.1.1/lib/launch/index.js
     // https://github.com/karma-runner/karma-firefox-launcher/blob/v2.1.3/index.js
     logger.debug('firefox_prefs_create', 'Creating temporary prefs.js file');
-    fs.writeFileSync(path.join(profileDir, 'prefs.js'), FirefoxBrowser.createPrefsJs({
+    fs.writeFileSync(path.join(profileDir, 'prefs.js'), FirefoxBrowser.#createPrefsJs({
       'app.update.disabledForTesting': true, // Disable auto-updates
       'browser.sessionstore.resume_from_crash': false,
       'browser.shell.checkDefaultBrowser': false,
@@ -234,9 +235,22 @@ class FirefoxBrowser {
     }));
 
     try {
-      await LocalBrowser.spawn(this.getCandidates(), args, signal, logger);
+      await LocalBrowser.spawn(FirefoxBrowser.#getCandidates(), args, signal, logger);
     } finally {
-      fs.rmSync(profileDir, { recursive: true, force: true });
+      // On Windows, when spawn() returns after firefox.exe has stopped, it sometimes can't delete
+      // some temporary files yet as they're somehow still in use (EBUSY). Perhaps a race condition,
+      // or an lagged background process?
+      // > BUSY: resource busy or locked,
+      // > unlink 'C:\Users\RUNNER~1\AppData\Local\Temp\qtap_EZ4IoO\bounce-tracking-protection.sqlite'
+      // Enable `maxRetries` to cover the common case, and beyond that try-catch
+      // as it is not critical for test completion.
+      // TODO: Can we abstract this so that it happens automatically for any directory
+      // obtained via LocalBrowser.makeTempDir?
+      try {
+        fs.rmSync(profileDir, { recursive: true, force: true, maxRetries: 2 });
+      } catch (e) {
+        logger.warning('firefox_cleanup_fail', e);
+      }
     }
   }
 }

src/qtap.js

@@ -87,6 +87,12 @@ async function run (browserNames, files, options) {
     // exits naturally by itself.
     // TODO: Consider just calling process.exit after this await.
     // Is that faster and safe? What if any important clean up would we miss?
+    // 1. Removing of temp directories is generally done in browser "launch" functions
+    //    after the child process has properly ended (and has to, as otherwise the
+    //    files are likely still locked and/or may end up re-created). If we were to
+    //    exit earlier, we may leave temp directories behind. This is fine when running
+    //    in an ephemeral environment (e.g. CI), but not great for local dev.
+    //
     await Promise.allSettled(browserLaunches);
     // Await again, so that any error gets thrown accordingly,
     // we don't do this directly because we first want to wait for all tests