Fix #7: persist undo and redo results immediately

tests/test_main.py

@@ -986,6 +986,108 @@ class TestHostsManagerApp:
             # Should start DNS resolution
             app.run_worker.assert_called()
 
+    def test_undo_saves_the_reverted_hosts_file(self):
+        """Undo persists its result before refreshing the interface."""
+        with patch("hosts.tui.app.HostsParser"), patch("hosts.tui.app.Config"):
+            app = HostsManagerApp()
+            app.edit_mode = True
+            app.manager.edit_mode = True
+            app.hosts_file = HostsFile()
+            entry = HostEntry(ip_address="192.168.1.1", hostnames=["test.local"])
+            app.hosts_file.add_entry(entry)
+            app.manager.execute_toggle_command(app.hosts_file, 0)
+            app.manager.save_hosts_file = Mock(return_value=(True, "Hosts file saved"))
+            app.table_handler.populate_entries_table = Mock()
+            app.details_handler.update_entry_details = Mock()
+            app.update_status = Mock()
+
+            app.action_undo()
+
+            assert entry.is_active is True
+            app.manager.save_hosts_file.assert_called_once_with(app.hosts_file)
+            app.table_handler.populate_entries_table.assert_called_once()
+            app.details_handler.update_entry_details.assert_called_once()
+
+    def test_undo_save_failure_restores_the_persisted_state(self):
+        """Undo failure leaves the display and undo history at the saved state."""
+        with patch("hosts.tui.app.HostsParser"), patch("hosts.tui.app.Config"):
+            app = HostsManagerApp()
+            app.edit_mode = True
+            app.manager.edit_mode = True
+            app.hosts_file = HostsFile()
+            entry = HostEntry(ip_address="192.168.1.1", hostnames=["test.local"])
+            app.hosts_file.add_entry(entry)
+            app.manager.execute_toggle_command(app.hosts_file, 0)
+            app.manager.save_hosts_file = Mock(
+                return_value=(False, "Permission denied")
+            )
+            app.table_handler.populate_entries_table = Mock()
+            app.details_handler.update_entry_details = Mock()
+            app.update_status = Mock()
+
+            app.action_undo()
+
+            assert entry.is_active is False
+            assert app.manager.can_undo()
+            assert not app.manager.can_redo()
+            app.table_handler.populate_entries_table.assert_not_called()
+            app.details_handler.update_entry_details.assert_not_called()
+            app.update_status.assert_called_once_with(
+                "❌ Undo save failed; previous state restored: Permission denied"
+            )
+
+    def test_redo_saves_the_reapplied_hosts_file(self):
+        """Redo persists its result before refreshing the interface."""
+        with patch("hosts.tui.app.HostsParser"), patch("hosts.tui.app.Config"):
+            app = HostsManagerApp()
+            app.edit_mode = True
+            app.manager.edit_mode = True
+            app.hosts_file = HostsFile()
+            entry = HostEntry(ip_address="192.168.1.1", hostnames=["test.local"])
+            app.hosts_file.add_entry(entry)
+            app.manager.execute_toggle_command(app.hosts_file, 0)
+            app.manager.undo_last_operation(app.hosts_file)
+            app.manager.save_hosts_file = Mock(return_value=(True, "Hosts file saved"))
+            app.table_handler.populate_entries_table = Mock()
+            app.details_handler.update_entry_details = Mock()
+            app.update_status = Mock()
+
+            app.action_redo()
+
+            assert entry.is_active is False
+            app.manager.save_hosts_file.assert_called_once_with(app.hosts_file)
+            app.table_handler.populate_entries_table.assert_called_once()
+            app.details_handler.update_entry_details.assert_called_once()
+
+    def test_redo_save_failure_restores_the_persisted_state(self):
+        """Redo failure leaves the display and redo history at the saved state."""
+        with patch("hosts.tui.app.HostsParser"), patch("hosts.tui.app.Config"):
+            app = HostsManagerApp()
+            app.edit_mode = True
+            app.manager.edit_mode = True
+            app.hosts_file = HostsFile()
+            entry = HostEntry(ip_address="192.168.1.1", hostnames=["test.local"])
+            app.hosts_file.add_entry(entry)
+            app.manager.execute_toggle_command(app.hosts_file, 0)
+            app.manager.undo_last_operation(app.hosts_file)
+            app.manager.save_hosts_file = Mock(
+                return_value=(False, "Permission denied")
+            )
+            app.table_handler.populate_entries_table = Mock()
+            app.details_handler.update_entry_details = Mock()
+            app.update_status = Mock()
+
+            app.action_redo()
+
+            assert entry.is_active is True
+            assert not app.manager.can_undo()
+            assert app.manager.can_redo()
+            app.table_handler.populate_entries_table.assert_not_called()
+            app.details_handler.update_entry_details.assert_not_called()
+            app.update_status.assert_called_once_with(
+                "❌ Redo save failed; previous state restored: Permission denied"
+            )
+
     def test_main_function(self):
         """Test main entry point function."""
         with patch("hosts.main.HostsManagerApp") as mock_app_class: