Add debugging for iOS startup test flakes (#130099)

Adding debugging for https://github.com/flutter/flutter/issues/129836.

Takes a screenshot when startup test takes too long (10 minutes).

Also, removes some old debugging and add new debugging message.

dev/devicelab/lib/tasks/perf_tests.dart

@@ -771,6 +771,15 @@ class StartupTest {
       const int maxFailures = 3;
       int currentFailures = 0;
       for (int i = 0; i < iterations; i += 1) {
+        // Startup should not take more than a few minutes. After 10 minutes,
+        // take a screenshot to help debug.
+        final Timer timer = Timer(const Duration(minutes: 10), () async {
+          print('Startup not completed within 10 minutes. Taking a screenshot...');
+          await _flutterScreenshot(
+            device.deviceId,
+            'screenshot_startup_${DateTime.now().toLocal().toIso8601String()}.png',
+          );
+        });
         final int result = await flutter('run', options: <String>[
           '--no-android-gradle-daemon',
           '--no-publish-port',
@@ -782,7 +791,8 @@ class StartupTest {
           device.deviceId,
           if (applicationBinaryPath != null)
             '--use-application-binary=$applicationBinaryPath',
-         ], canFail: true);
+        ], canFail: true);
+        timer.cancel();
         if (result == 0) {
           final Map<String, dynamic> data = json.decode(
             file('${_testOutputDirectory(testDirectory)}/start_up_info.json').readAsStringSync(),
@@ -790,20 +800,10 @@ class StartupTest {
           results.add(data);
         } else {
           currentFailures += 1;
-          if (hostAgent.dumpDirectory != null) {
-            await flutter(
-              'screenshot',
-              options: <String>[
-                '-d',
-                device.deviceId,
-                '--out',
-                hostAgent.dumpDirectory!
-                    .childFile('screenshot_startup_failure_$currentFailures.png')
-                    .path,
-              ],
-              canFail: true,
-            );
-          }
+          await _flutterScreenshot(
+            device.deviceId,
+            'screenshot_startup_failure_$currentFailures.png',
+          );
           i -= 1;
           if (currentFailures == maxFailures) {
             return TaskResult.failure('Application failed to start $maxFailures times');
@@ -829,6 +829,23 @@ class StartupTest {
       ]);
     });
   }
+
+  Future<void> _flutterScreenshot(String deviceId, String screenshotName) async {
+    if (hostAgent.dumpDirectory != null) {
+      await flutter(
+        'screenshot',
+        options: <String>[
+          '-d',
+          deviceId,
+          '--out',
+          hostAgent.dumpDirectory!
+              .childFile(screenshotName)
+              .path,
+        ],
+        canFail: true,
+      );
+    }
+  }
 }
 
 /// A one-off test to verify that devtools starts in profile mode.

packages/flutter_tools/lib/src/ios/ios_deploy.dart

@@ -338,6 +338,8 @@ class IOSDeployDebugger {
     RegExp lldbRun = RegExp(r'\(lldb\)\s*run');
 
     final Completer<bool> debuggerCompleter = Completer<bool>();
+
+    bool receivedLogs = false;
     try {
       _iosDeployProcess = await _processUtils.start(
         _launchCommand,
@@ -386,8 +388,6 @@ class IOSDeployDebugger {
         if (lldbRun.hasMatch(line)) {
           _logger.printTrace(line);
           _debuggerState = _IOSDeployDebuggerState.launching;
-          // TODO(vashworth): Remove all debugger state comments when https://github.com/flutter/flutter/issues/126412 is resolved.
-          _logger.printTrace('Debugger state set to launching.');
           return;
         }
         // Next line after "run" must be "success", or the attach failed.
@@ -396,7 +396,6 @@ class IOSDeployDebugger {
           _logger.printTrace(line);
           final bool attachSuccess = line == 'success';
           _debuggerState = attachSuccess ? _IOSDeployDebuggerState.attached : _IOSDeployDebuggerState.detached;
-          _logger.printTrace('Debugger state set to ${attachSuccess ? 'attached' : 'detached'}.');
           if (!debuggerCompleter.isCompleted) {
             debuggerCompleter.complete(attachSuccess);
           }
@@ -425,7 +424,6 @@ class IOSDeployDebugger {
           // Even though we're not "detached", just stopped, mark as detached so the backtrace
           // is only show in verbose.
           _debuggerState = _IOSDeployDebuggerState.detached;
-          _logger.printTrace('Debugger state set to detached.');
 
           // If we paused the app and are waiting to resume it, complete the completer
           final Completer<void>? processResumeCompleter = _processResumeCompleter;
@@ -465,7 +463,6 @@ class IOSDeployDebugger {
           _logger.printTrace(line);
           // we marked this detached when we received [_backTraceAll]
           _debuggerState = _IOSDeployDebuggerState.attached;
-          _logger.printTrace('Debugger state set to attached.');
           return;
         }
 
@@ -480,6 +477,16 @@ class IOSDeployDebugger {
           // This will still cause "legit" logged newlines to be doubled...
         } else if (!_debuggerOutput.isClosed) {
           _debuggerOutput.add(line);
+
+          // Sometimes the `ios-deploy` process does not return logs from the
+          // application after attaching, such as the Dart VM url. In CI,
+          // `idevicesyslog` is used as a fallback to get logs. Print a
+          // message to indicate whether logs were received from `ios-deploy`
+          // to help with debugging.
+          if (!receivedLogs) {
+            _logger.printTrace('Received logs from ios-deploy.');
+            receivedLogs = true;
+          }
         }
         lastLineFromDebugger = line;
       });

packages/flutter_tools/test/general.shard/ios/ios_deploy_test.dart

@@ -341,6 +341,33 @@ void main () {
         await iosDeployDebugger.launchAndAttach();
         expect(logger.errorText, contains('Try launching from within Xcode'));
       });
+
+      testWithoutContext('debugger attached and received logs', () async {
+        final StreamController<List<int>> stdin = StreamController<List<int>>();
+        final FakeProcessManager processManager = FakeProcessManager.list(<FakeCommand>[
+          FakeCommand(
+            command: const <String>['ios-deploy'],
+            stdout: '(lldb)     run\r\nsuccess\r\nLog on attach1\r\n\r\nLog on attach2\r\n',
+            stdin: IOSink(stdin.sink),
+          ),
+        ]);
+        final IOSDeployDebugger iosDeployDebugger = IOSDeployDebugger.test(
+          processManager: processManager,
+          logger: logger,
+        );
+        final List<String> receivedLogLines = <String>[];
+        final Stream<String> logLines = iosDeployDebugger.logLines
+          ..listen(receivedLogLines.add);
+
+        expect(iosDeployDebugger.logLines, emitsInOrder(<String>[
+          'Log on attach1',
+          'Log on attach2',
+        ]));
+        expect(await iosDeployDebugger.launchAndAttach(), isTrue);
+        await logLines.drain();
+
+        expect(LineSplitter.split(logger.traceText), containsOnce('Received logs from ios-deploy.'));
+      });
     });
 
     testWithoutContext('detach', () async {