Check for devicectl launch logs from std and file

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

@@ -335,6 +335,8 @@ class IOSCoreDeviceControl {
     'Failed to execute code (error: EXC_BAD_ACCESS, debugger assist: not detected)',
   ];
 
+  static const kCoreDeviceLaunchCompleteLog = 'Waiting for the application to terminate';
+
   /// Executes `devicectl` command to get list of devices. The command will
   /// likely complete before [timeout] is reached. If [timeout] is reached,
   /// the command will be stopped as a failure.
@@ -650,13 +652,21 @@ class IOSCoreDeviceControl {
   ///
   /// If [attachToConsole] is true, attaches the application to the console and waits for the app
   /// to terminate.
+  ///
+  /// When [jsonOutputFile] is provided, devicectl will write a JSON file with the command results
+  /// after the command has completed. This will not have the results when using [attachToConsole]
+  /// until the process has exited.
+  ///
+  /// When [logOutputFile] is provided, devicectl will write all logging otherwise passed to
+  /// stdout/stderr to the file. It will also continue to stream the logs to stdout/stderr.
   List<String> _launchAppCommand({
     required String deviceId,
     required String bundleId,
     List<String> launchArguments = const <String>[],
     bool startStopped = false,
     bool attachToConsole = false,
-    File? outputFile,
+    File? jsonOutputFile,
+    File? logOutputFile,
   }) {
     return <String>[
       ..._xcode.xcrunCommand(),
@@ -674,7 +684,8 @@ class IOSCoreDeviceControl {
         // See https://github.com/llvm/llvm-project/blob/19b43e1757b4fd3d0f188cf8a08e9febb0dbec2f/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp#L1227-L1233
         '{"OS_ACTIVITY_DT_MODE": "enable"}',
       ],
-      if (outputFile != null) ...<String>['--json-output', outputFile.path],
+      if (jsonOutputFile != null) ...<String>['--json-output', jsonOutputFile.path],
+      if (logOutputFile != null) ...<String>['--log-output', logOutputFile.path],
       bundleId,
       if (launchArguments.isNotEmpty) ...launchArguments,
     ];
@@ -703,7 +714,7 @@ class IOSCoreDeviceControl {
       deviceId: deviceId,
       launchArguments: launchArguments,
       startStopped: startStopped,
-      outputFile: output,
+      jsonOutputFile: output,
     );
 
     try {
@@ -754,15 +765,19 @@ class IOSCoreDeviceControl {
       return false;
     }
 
+    final Directory tempDirectory = _fileSystem.systemTempDirectory.createTempSync('core_devices.');
+    final File output = tempDirectory.childFile('launch_log.txt')..createSync();
+
     final launchCompleter = Completer<bool>();
     final List<String> command = _launchAppCommand(
       bundleId: bundleId,
       deviceId: deviceId,
       launchArguments: launchArguments,
       startStopped: startStopped,
       attachToConsole: true,
+      logOutputFile: output,
     );
-
+    Timer? timer;
     try {
       final Process launchProcess = await _processUtils.start(command);
       coreDeviceLogForwarder.launchProcess = launchProcess;
@@ -776,7 +791,7 @@ class IOSCoreDeviceControl {
               _logger.printTrace(line);
             }
 
-            if (line.contains('Waiting for the application to terminate')) {
+            if (!launchCompleter.isCompleted && line.contains(kCoreDeviceLaunchCompleteLog)) {
               launchCompleter.complete(true);
             }
           });
@@ -805,10 +820,27 @@ class IOSCoreDeviceControl {
               }
             }),
       );
-      return launchCompleter.future;
+
+      // Sometimes devicectl launch logs don't stream to stdout.
+      // As a workaround, we also use the log output file to check if it has finished launching.
+      timer = Timer.periodic(const Duration(seconds: 1), (timer) async {
+        if (await output.exists()) {
+          final String contents = await output.readAsString();
+          if (!launchCompleter.isCompleted && contents.contains(kCoreDeviceLaunchCompleteLog)) {
+            launchCompleter.complete(true);
+          }
+        }
+      });
+
+      // Do not return the launchCompleter.future directly, otherwise, the timer will be canceled
+      // prematurely.
+      final bool status = await launchCompleter.future;
+      return status;
     } on ProcessException catch (err) {
       _logger.printTrace('Error executing devicectl: $err');
       return false;
+    } finally {
+      timer?.cancel();
     }
   }
 

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

@@ -1791,6 +1791,8 @@ invalid JSON
               '--console',
               '--environment-variables',
               '{"OS_ACTIVITY_DT_MODE": "enable"}',
+              '--log-output',
+              '/.tmp_rand0/core_devices.rand0/launch_log.txt',
               bundleId,
             ],
             stdout: '''
@@ -1830,6 +1832,8 @@ Waiting for the application to terminate...
               '--console',
               '--environment-variables',
               '{"OS_ACTIVITY_DT_MODE": "enable"}',
+              '--log-output',
+              '/.tmp_rand0/core_devices.rand0/launch_log.txt',
               bundleId,
               '--arg1',
               '--arg2',
@@ -1872,6 +1876,8 @@ Waiting for the application to terminate...
               '--console',
               '--environment-variables',
               '{"OS_ACTIVITY_DT_MODE": "enable"}',
+              '--log-output',
+              '/.tmp_rand0/core_devices.rand0/launch_log.txt',
               bundleId,
             ],
             stdout: '''
@@ -1939,6 +1945,8 @@ Waiting for the application to terminate...
               '--console',
               '--environment-variables',
               '{"OS_ACTIVITY_DT_MODE": "enable"}',
+              '--log-output',
+              '/.tmp_rand0/core_devices.rand0/launch_log.txt',
               bundleId,
             ],
             exitCode: 1,
@@ -1961,6 +1969,54 @@ ERROR: The operation couldn?t be completed. (OSStatus error -10814.) (NSOSStatus
         expect(logger.errorText, isEmpty);
         expect(result, isFalse);
       });
+
+      testWithoutContext('Successful launch with output in log file', () async {
+        final Completer<void> launchCompleter = Completer();
+        fakeProcessManager.addCommand(
+          FakeCommand(
+            command: const <String>[
+              'xcrun',
+              'devicectl',
+              'device',
+              'process',
+              'launch',
+              '--device',
+              deviceId,
+              '--start-stopped',
+              '--console',
+              '--environment-variables',
+              '{"OS_ACTIVITY_DT_MODE": "enable"}',
+              '--log-output',
+              '/.tmp_rand0/core_devices.rand0/launch_log.txt',
+              bundleId,
+            ],
+            onRun: (command) {
+              fileSystem.file('/.tmp_rand0/core_devices.rand0/launch_log.txt')
+                ..createSync(recursive: true)
+                ..writeAsStringSync('''
+10:04:12  Acquired tunnel connection to device.
+10:04:12  Enabling developer disk image services.
+10:04:12  Acquired usage assertion.
+Launched application with com.example.my_app bundle identifier.
+Waiting for the application to terminate...
+''');
+            },
+            completer: launchCompleter,
+          ),
+        );
+
+        final bool result = await deviceControl.launchAppAndStreamLogs(
+          deviceId: deviceId,
+          bundleId: bundleId,
+          coreDeviceLogForwarder: FakeIOSCoreDeviceLogForwarder(),
+          startStopped: true,
+        );
+        launchCompleter.complete();
+
+        expect(fakeProcessManager, hasNoRemainingExpectations);
+        expect(logger.errorText, isEmpty);
+        expect(result, isTrue);
+      });
     });
 
     group('terminate app', () {