DwRecordingServerTransport class

A DwServerTransport that answers reads from what the test prepared and keeps every write that left, for a test to assert on afterwards.

Hand it to DwCore instead of a client, and nothing has to stand up a Serverpod client to render a widget or watch it save:

final transport = DwRecordingServerTransport(
  classNames: {Task: 'Task'},
);

setUpAll(() {
  DwCore<ServerpodClientShared, Task>(
    config: const DwConfig(),
    transport: transport,
    dwAlerts: DwAlerts.init(logErrors: false, logFunction: (_) {}),
    getUserId: (_) => null,
  );
});

testWidgets('the button saves the task', (tester) async {
  await tester.pumpWidget(/* the feature */);
  await tester.tap(find.byIcon(Icons.check));
  await tester.pumpAndSettle();

  expect(transport.saves, hasLength(1));
  expect((transport.saves.single.model as Task).isDone, isTrue);
});

Reads must be prepared, writes need not be. A read nobody answered throws DwUnpreparedServerCall, because the test does not know what its subject fetches. A save answers by echoing the model back and a delete by succeeding, because there the assertion is about what left, and forcing a canned response for it would be ceremony with nothing behind it. Override either with answerSave / answerDelete when the response matters — an id assigned on insert, a rejected write.

One instance per core, and reset between tests: the core keeps the transport it was built with for its whole life, and DwCore can be built only once per process.