rely/test/integrations/backend/sync_envelope_validator_test.dart

import 'package:flutter_test/flutter_test.dart';
import 'package:relationship_saver/core/network/backend_exception.dart';
import 'package:relationship_saver/integrations/backend/models/backend_models.dart';
import 'package:relationship_saver/integrations/backend/sync_envelope_validator.dart';

void main() {
  test('rejects delete envelopes with payload', () {
    final ChangeEnvelope invalid = ChangeEnvelope(
      schemaVersion: 1,
      entityType: 'person',
      entityId: 'p1',
      op: ChangeOperation.delete,
      modifiedAt: DateTime.utc(2026, 1, 1),
      clientMutationId: 'cm-delete',
      payload: const <String, dynamic>{'unexpected': true},
    );

    expect(
      () => SyncEnvelopeValidator.validate(invalid),
      throwsA(isA<ValidationException>()),
    );
  });

  test('accepts valid upsert envelope', () {
    final ChangeEnvelope valid = ChangeEnvelope(
      schemaVersion: 1,
      entityType: 'person',
      entityId: 'p2',
      op: ChangeOperation.upsert,
      modifiedAt: DateTime.utc(2026, 1, 1),
      clientMutationId: 'cm-upsert',
      payload: const <String, dynamic>{'name': 'Jamie'},
    );

    expect(() => SyncEnvelopeValidator.validate(valid), returnsNormally);
  });
}