From dce18b6fd9d0310b9016ddb383b8e21b9e065ae2 Mon Sep 17 00:00:00 2001
From: Jason Simmons <jason-simmons@users.noreply.github.com>
Date: Tue, 6 May 2025 23:43:07 +0000
Subject: [PATCH] Capture errors when running flutter_tools in the
 entrypoint_dart_registrant devicelab test (#168411)

See https://github.com/flutter/flutter/issues/168405
---
 .../lib/tasks/entrypoint_dart_registrant.dart       | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/dev/devicelab/lib/tasks/entrypoint_dart_registrant.dart b/dev/devicelab/lib/tasks/entrypoint_dart_registrant.dart
index 83971f2590a..b07bce22a4e 100644
--- a/dev/devicelab/lib/tasks/entrypoint_dart_registrant.dart
+++ b/dev/devicelab/lib/tasks/entrypoint_dart_registrant.dart
@@ -72,8 +72,19 @@ Future<TaskResult> _runWithTempDir(Directory tempDir) async {
             completer.complete(line);
           }
         });
-    final String entrypoint = await completer.future;
+    final StreamSubscription<String> stderrSub = process.stderr
+        .transform<String>(const Utf8Decoder())
+        .transform<String>(const LineSplitter())
+        .listen((String line) async {
+          print(line);
+        });
+    final Object result = await Future.any(<Future<Object>>[completer.future, process.exitCode]);
+    if (result is int) {
+      throw Exception('flutter run failed, exitCode=$result');
+    }
+    final String entrypoint = result as String;
     await stdoutSub.cancel();
+    await stderrSub.cancel();
     process.stdin.write('q');
     await process.stdin.flush();
     process.kill(ProcessSignal.sigint);