print launching on device message (#39748)

packages/flutter_tools/lib/src/build_runner/resident_web_runner.dart

@@ -57,7 +57,7 @@ class ResidentWebRunner extends ResidentRunner {
     @required DebuggingOptions debuggingOptions,
   }) : super(
           <FlutterDevice>[],
-          target: target,
+          target: target ?? fs.path.join('lib', 'main.dart'),
           debuggingOptions: debuggingOptions,
           ipv6: ipv6,
           stayResident: true,
@@ -158,6 +158,8 @@ class ResidentWebRunner extends ResidentRunner {
       printError(message);
       return 1;
     }
+    final String modeName = debuggingOptions.buildInfo.friendlyModeName;
+    printStatus('Launching ${getDisplayPath(target)} on ${device.name} in $modeName mode...');
     Status buildStatus;
     try {
       buildStatus = logger.startProgress('Building application for the web...', timeout: null);

packages/flutter_tools/test/general.shard/resident_web_runner_test.dart

@@ -28,12 +28,13 @@ void main() {
   ResidentWebRunner residentWebRunner;
   MockDebugConnection mockDebugConnection;
   MockVmService mockVmService;
+  MockWebDevice mockWebDevice;
 
   setUp(() {
     mockWebFs = MockFlutterWebFs();
     mockDebugConnection = MockDebugConnection();
     mockVmService = MockVmService();
-    final MockWebDevice mockWebDevice = MockWebDevice();
+    mockWebDevice = MockWebDevice();
     testbed = Testbed(
       setup: () {
         residentWebRunner = ResidentWebRunner(
@@ -357,6 +358,20 @@ void main() {
     await residentWebRunner.exit();
     await residentWebRunner.exit();
   }));
+
+  test('Prints target and device name on run', () => testbed.run(() async {
+    _setupMocks();
+    when(mockWebDevice.name).thenReturn('Chromez');
+    final Completer<DebugConnectionInfo> connectionInfoCompleter = Completer<DebugConnectionInfo>();
+     unawaited(residentWebRunner.run(
+      connectionInfoCompleter: connectionInfoCompleter,
+    ));
+    await connectionInfoCompleter.future;
+
+    final BufferLogger bufferLogger = logger;
+
+    expect(bufferLogger.statusText, contains('Launching ${fs.path.join('lib', 'main.dart')} on Chromez in debug mode'));
+  }));
 }