feat: add TestRunViewModel with state management

lib/ui/features/test_run/test_run_view_model.dart

@@ -0,0 +1,58 @@
+import 'package:flutter/foundation.dart';
+import 'package:iperf3gui/data/services/iperf3_service.dart';
+import 'package:iperf3gui/domain/models/test_configuration.dart';
+import 'package:iperf3gui/domain/models/iperf3_result.dart';
+
+/// State of the test run.
+enum TestRunState { idle, running, completed, error }
+
+/// ViewModel for managing test run state.
+class TestRunViewModel extends ChangeNotifier {
+  final Iperf3Service _iperf3Service;
+
+  TestRunState _state = TestRunState.idle;
+  TestRunState get state => _state;
+
+  Iperf3Result? _result;
+  Iperf3Result? get result => _result;
+
+  TestConfiguration? _currentConfig;
+  TestConfiguration? get currentConfig => _currentConfig;
+
+  TestRunViewModel({required Iperf3Service iperf3Service})
+      : _iperf3Service = iperf3Service;
+
+  /// Start a test with the given configuration.
+  Future<void> runTest(TestConfiguration config) async {
+    if (!config.isValid) {
+      _state = TestRunState.error;
+      notifyListeners();
+      return;
+    }
+
+    _state = TestRunState.running;
+    _currentConfig = config;
+    _result = null;
+    notifyListeners();
+
+    try {
+      final result = await _iperf3Service.run(config);
+      _result = result;
+      _state = result.exitCode == 0
+          ? TestRunState.completed
+          : TestRunState.error;
+    } catch (e) {
+      _state = TestRunState.error;
+    } finally {
+      notifyListeners();
+    }
+  }
+
+  /// Reset to idle state.
+  void reset() {
+    _state = TestRunState.idle;
+    _result = null;
+    _currentConfig = null;
+    notifyListeners();
+  }
+}

test/ui/features/test_run/test_run_view_model_test.dart

@@ -0,0 +1,61 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:iperf3gui/data/services/iperf3_service.dart';
+import 'package:iperf3gui/domain/models/iperf3_result.dart';
+import 'package:iperf3gui/domain/models/test_configuration.dart';
+import 'package:iperf3gui/ui/features/test_run/test_run_view_model.dart';
+
+void main() {
+  group('TestRunViewModel', () {
+    test('starts in idle state', () {
+      final vm = TestRunViewModel(
+        iperf3Service: _MockIperf3Service(),
+      );
+      expect(vm.state, equals(TestRunState.idle));
+      expect(vm.result, isNull);
+      expect(vm.currentConfig, isNull);
+    });
+
+    test('can be reset', () {
+      final vm = TestRunViewModel(
+        iperf3Service: _MockIperf3Service(),
+      );
+      vm.reset();
+      expect(vm.state, equals(TestRunState.idle));
+    });
+
+    test('invalid config sets error state without running', () async {
+      final vm = TestRunViewModel(
+        iperf3Service: _MockIperf3Service(),
+      );
+      const config = TestConfiguration(server: '');
+      await vm.runTest(config);
+      expect(vm.state, equals(TestRunState.error));
+    });
+
+    test('runTest with valid config calls service', () async {
+      final mock = _MockIperf3Service(
+        onRun: (config) async {
+          expect(config.server, equals('192.168.1.1'));
+          return Iperf3Result(rawOutput: 'done', exitCode: 0);
+        },
+      );
+      final vm = TestRunViewModel(iperf3Service: mock);
+      const config = TestConfiguration(server: '192.168.1.1');
+      await vm.runTest(config);
+      expect(vm.state, equals(TestRunState.completed));
+      expect(vm.result, isNotNull);
+    });
+  });
+}
+
+class _MockIperf3Service implements Iperf3Service {
+  _MockIperf3Service({this.onRun});
+
+  final Future<Iperf3Result> Function(TestConfiguration)? onRun;
+
+  @override
+  Future<Iperf3Result> run(TestConfiguration config) async {
+    if (onRun != null) return onRun!(config);
+    return Iperf3Result(rawOutput: '', exitCode: 0);
+  }
+}