Fix a bug with detecting DevTools server availability (#9189)

Author: kenzieschmoll

packages/devtools_app/lib/src/shared/preferences/preferences.dart

@@ -20,6 +20,7 @@ import '../diagnostics/inspector_service.dart';
 import '../feature_flags.dart';
 import '../globals.dart';
 import '../primitives/query_parameters.dart';
+import '../server/server.dart';
 import '../utils/utils.dart';
 
 part '_cpu_profiler_preferences.dart';
@@ -216,12 +217,6 @@ class PreferencesController extends DisposableController
       return;
     }
 
-    // Whether DevTools was run using the `dt run` command, which runs DevTools
-    // using `flutter run` and connects it to a locally running instance of the
-    // DevTools server.
-    final usingDebugDevToolsServer =
-        (const String.fromEnvironment('debug_devtools_server')).isNotEmpty &&
-        !kReleaseMode;
     final shouldEnableWasm =
         (enabledFromStorage || enabledFromQueryParams) &&
         kIsWeb &&

packages/devtools_app/lib/src/shared/server/_server_api.dart

@@ -11,7 +11,7 @@ Future<bool> checkServerHttpApiAvailable() async {
     // in the server in the SDK (see `pkg\dds\lib\src\devtools\handler.dart`)
     // and not delegated back to DevTools shared code.
     final response = await get(
-      Uri.parse('${apiPrefix}ping'),
+      buildDevToolsServerRequestUri('${apiPrefix}ping'),
     ).timeout(const Duration(seconds: 5));
     // When running with the local dev server Flutter may serve its index page
     // for missing files to support the hashless url strategy. Check the response

packages/devtools_app/lib/src/shared/server/server.dart

@@ -47,31 +47,43 @@ final _log = Logger('devtools_server_client');
 bool get isDevToolsServerAvailable =>
     kIsWeb && storage is ServerConnectionStorage;
 
-const _debugDevToolsServerFlag = 'debug_devtools_server';
+const _debugDevToolsServerEnvironmentVariable = String.fromEnvironment(
+  'debug_devtools_server',
+);
+
+/// Whether DevTools was run using the `dt run` command, which runs DevTools in
+/// debug mode using `flutter run` and connects it to an instance of the
+/// DevTools server.
+bool get usingDebugDevToolsServer =>
+    _debugDevToolsServerEnvironmentVariable.isNotEmpty && !kReleaseMode;
 
 String get devToolsServerUriAsString {
-  const debugDevToolsServerUriAsString = String.fromEnvironment(
-    _debugDevToolsServerFlag,
-  );
   // Ensure we only use the debug DevTools server URI in non-release
   // builds. By running `dt run`, an instance of DevTools run with `flutter run`
   // can be connected to the DevTools server on a different port.
-  return debugDevToolsServerUriAsString.isNotEmpty && !kReleaseMode
-      ? debugDevToolsServerUriAsString
+  return usingDebugDevToolsServer
+      ? _debugDevToolsServerEnvironmentVariable
       : Uri.base.toString();
 }
 
+/// Helper to build a request URI to the DevTools server, which may not be on
+/// the same origin as the DevTools app window.
+Uri buildDevToolsServerRequestUri(String url) {
+  // [_debugDevToolsServerEnvironmentVariable] will be the empty string if the
+  // [_debugDevToolsServerFlag] environment variable declaration was not set
+  // using `--dart-define`.
+  const baseUri = _debugDevToolsServerEnvironmentVariable;
+  return Uri.parse(path.join(baseUri, url));
+}
+
 /// Helper to catch any server request which could fail.
 ///
 /// Returns HttpRequest or null (if server failure).
 Future<Response?> request(String url) async {
   Response? response;
 
   try {
-    // This will be the empty string if this environment declaration was not
-    // set using `--dart-define`.
-    const baseUri = String.fromEnvironment(_debugDevToolsServerFlag);
-    response = await post(Uri.parse(path.join(baseUri, url)));
+    response = await post(buildDevToolsServerRequestUri(url));
   } catch (_) {}
 
   return response;

packages/devtools_app/test/shared/utils/future_work_tracker_test.dart

@@ -75,7 +75,7 @@ void main() {
 
     test('tracks failed work', () {
       _wrapAndRunAsync((async) async {
-        await runZonedGuarded(
+        runZonedGuarded(
           () {
             final tracker = FutureWorkTracker();
             expect(tracker.active.value, isFalse);