fix(#118): corrije erro no command

lib/core/state/command.dart

@@ -5,12 +5,22 @@ abstract class Command<T> extends ChangeNotifier {
   Result<T>? _result;
 
   bool _running = false;
+  bool _isError = false;
+  bool _isOk = false;
 
   Command();
 
-  bool get isError => result?.asError != null;
+  bool get isError {
+    bool tmp = _isError;
+    _isError = false;
+    return tmp;
+  }
 
-  bool get isOk => result?.asValue != null;
+  bool get isOk {
+    bool tmp = _isOk;
+    _isOk = false;
+    return tmp;
+  }
 
   Result<T>? get result => _result;
 
@@ -21,14 +31,24 @@ abstract class Command<T> extends ChangeNotifier {
 
     _result = null;
     _running = true;
+    _isOk = false;
+    _isError = false;
     notifyListeners();
 
     try {
       _result = await action();
+
+      if (_result?.asError != null) {
+        _isError = true;
+      } else {
+        _isOk = true;
+      }
+
     } catch (e) {
       _result = Result.error(e);
+      _isError = true;
     } finally {
-    _running = false;
+      _running = false;
       notifyListeners();
     }
   }

test/core/state/command_test.dart

@@ -0,0 +1,102 @@
+import 'package:aranduapp/core/state/command.dart';
+import 'package:async/async.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  test('Successful execution updates state and result', () async {
+    Command0<String> command = Command0(() async {
+      await Future.delayed(const Duration(seconds: 1));
+      return Result.value('Success');
+    });
+
+    expect(command.running, false);
+    expect(command.result, null);
+
+    final future = command.execute();
+
+    expect(command.running, true);
+    await future;
+
+    expect(command.running, false);
+    expect(command.isOk, true);
+    expect(command.result?.asValue?.value, 'Success');
+  });
+
+  test('Execution with error updates state and sets error', () async {
+    Command0<String> command = Command0(() async {
+      throw Exception('An error occurred');
+    });
+
+    expect(command.running, false);
+    expect(command.result, null);
+
+    final future = command.execute();
+
+    expect(command.running, true);
+    await future;
+
+    expect(command.running, false);
+    expect(command.isError, true);
+    expect(command.result?.asError?.error, isA<Exception>());
+  });
+
+  test('No re-execution when already running', () async {
+    //TODO: No re-execution when already running
+  });
+
+  test('Notifies listeners on state changes', () async {
+    Command0<String> command = Command0(() async => Result.value('Success'));
+
+    int notifyCount = 0;
+    command.addListener(() {
+      notifyCount++;
+    });
+
+    await command.execute();
+
+    expect(notifyCount, greaterThan(0));
+  });
+
+  test('Result on second access is ok', () async {
+    Command0<String> command = Command0(() async => Result.value('Success'));
+
+    await command.execute();
+
+    final firstAccess = command.isOk;
+
+    final secondAccess = command.isOk;
+
+    expect(firstAccess, true);
+    expect(command.result!.asValue!.value, 'Success');
+    expect(secondAccess, false);
+  });
+
+  test('Result on second access is error', () async {
+    Command0<String> command = Command0(() async => Result.error('error'));
+
+    await command.execute();
+
+    final firstAccess = command.isError;
+
+    final secondAccess = command.isError;
+
+    expect(firstAccess, true);
+    expect(command.result!.asError!.error, 'error');
+    expect(secondAccess, false);
+  });
+
+  test('Result on second access is error with exception', () async {
+    Command0<String> command = Command0(() async => throw Exception('error'));
+
+    await command.execute();
+
+    final firstAccess = command.isError;
+
+    final secondAccess = command.isError;
+
+    expect(firstAccess, true);
+    expect(
+        command.result?.asError?.error.toString(), equals('Exception: error'));
+    expect(secondAccess, false);
+  });
+}