[flutter_tools] Make AndroidConsole check for next line (#52353)

packages/flutter_tools/lib/src/android/android_console.dart

@@ -42,21 +42,29 @@ class AndroidConsole {
   }
 
   Future<String> getAvdName() async {
+    if (_queue == null) {
+      return null;
+    }
     _write('avd name\n');
     return _readResponse();
   }
 
   void destroy() {
-    if (_socket != null) {
-      _socket.destroy();
-      _socket = null;
-      _queue = null;
-    }
+    _socket?.destroy();
+    _socket = null;
+    _queue = null;
   }
 
   Future<String> _readResponse() async {
+    if (_queue == null) {
+      return null;
+    }
     final StringBuffer output = StringBuffer();
     while (true) {
+      if (!await _queue.hasNext) {
+        destroy();
+        return null;
+      }
       final String text = await _queue.next;
       final String trimmedText = text.trim();
       if (trimmedText == 'OK') {
@@ -72,6 +80,6 @@ class AndroidConsole {
   }
 
   void _write(String text) {
-    _socket.add(ascii.encode(text));
+    _socket?.add(ascii.encode(text));
   }
 }

packages/flutter_tools/test/general.shard/android/android_device_test.dart

@@ -523,6 +523,8 @@ flutter:
     const String dummyEmulatorId = 'dummyEmulatorId';
     final Future<Socket> Function(String host, int port) unresponsiveSocket =
         (String host, int port) async => MockUnresponsiveAndroidConsoleSocket();
+    final Future<Socket> Function(String host, int port) disconnectingSocket =
+        (String host, int port) async => MockDisconnectingAndroidConsoleSocket();
     final Future<Socket> Function(String host, int port) workingSocket =
         (String host, int port) async => MockWorkingAndroidConsoleSocket(dummyEmulatorId);
     String hardware;
@@ -597,6 +599,14 @@ flutter:
       AndroidConsoleSocketFactory: () => unresponsiveSocket,
       ProcessManager: () => mockProcessManager,
     });
+
+    testUsingContext('returns null on early disconnect', () async {
+      final AndroidDevice device = AndroidDevice('emulator-5555');
+      expect(await device.emulatorId, isNull);
+    }, overrides: <Type, Generator>{
+      AndroidConsoleSocketFactory: () => disconnectingSocket,
+      ProcessManager: () => mockProcessManager,
+    });
   });
 
   group('portForwarder', () {
@@ -980,6 +990,26 @@ class MockUnresponsiveAndroidConsoleSocket extends Mock implements Socket {
   void add(List<int> data) {}
 }
 
+/// An Android console socket that drops all input and returns no output.
+class MockDisconnectingAndroidConsoleSocket extends Mock implements Socket {
+  MockDisconnectingAndroidConsoleSocket() {
+    _controller.add('Android Console: Welcome!\n');
+    // Include OK in the same packet here. In the response to "avd name"
+    // it's sent alone to ensure both are handled.
+    _controller.add('Android Console: Some intro text\nOK\n');
+  }
+
+  final StreamController<String> _controller = StreamController<String>();
+
+  @override
+  Stream<E> asyncMap<E>(FutureOr<E> convert(Uint8List event)) => _controller.stream as Stream<E>;
+
+  @override
+  void add(List<int> data) {
+    _controller.close();
+  }
+}
+
 class AndroidPackageTest extends ApplicationPackage {
   AndroidPackageTest() : super(id: 'app-id');