fix flutter not finding custom device (#108884)

packages/flutter_tools/lib/src/doctor.dart

@@ -21,6 +21,7 @@ import 'base/terminal.dart';
 import 'base/user_messages.dart';
 import 'base/utils.dart';
 import 'cache.dart';
+import 'custom_devices/custom_device_workflow.dart';
 import 'device.dart';
 import 'doctor_validator.dart';
 import 'features.dart';
@@ -93,6 +94,10 @@ class _DefaultDoctorValidatorsProvider implements DoctorValidatorsProvider {
     featureFlags: featureFlags,
   );
 
+  late final CustomDeviceWorkflow customDeviceWorkflow = CustomDeviceWorkflow(
+    featureFlags: featureFlags,
+  );
+
   @override
   List<DoctorValidator> get validators {
     if (_validators != null) {
@@ -200,6 +205,9 @@ class _DefaultDoctorValidatorsProvider implements DoctorValidatorsProvider {
         _workflows!.add(webWorkflow);
       }
 
+      if (customDeviceWorkflow.appliesToHostPlatform) {
+        _workflows!.add(customDeviceWorkflow);
+      }
     }
     return _workflows!;
   }

packages/flutter_tools/test/commands.shard/hermetic/doctor_test.dart

@@ -17,6 +17,7 @@ import 'package:flutter_tools/src/base/user_messages.dart';
 import 'package:flutter_tools/src/build_info.dart';
 import 'package:flutter_tools/src/cache.dart';
 import 'package:flutter_tools/src/commands/doctor.dart';
+import 'package:flutter_tools/src/custom_devices/custom_device_workflow.dart';
 import 'package:flutter_tools/src/device.dart';
 import 'package:flutter_tools/src/doctor.dart';
 import 'package:flutter_tools/src/doctor_validator.dart';
@@ -750,6 +751,20 @@ void main() {
     ProcessManager: () => fakeProcessManager,
   });
 
+  testUsingContext('CustomDevicesWorkflow is a part of validator workflows if enabled', () async {
+    final List<Workflow> workflows = DoctorValidatorsProvider.test(
+      featureFlags: TestFeatureFlags(areCustomDevicesEnabled: true),
+      platform: FakePlatform(),
+    ).workflows;
+    expect(
+      workflows,
+      contains(isA<CustomDeviceWorkflow>()),
+    );
+  }, overrides: <Type, Generator>{
+    FileSystem: () => MemoryFileSystem.test(),
+    ProcessManager: () => fakeProcessManager,
+  });
+
   testUsingContext('Fetches tags to get the right version', () async {
     Cache.disableLocking();