void When(DealerManifestDownloadFailed e) => CheckFinished();
void Given(DealerManifestDownloadFailed e) => ManifestDownloadError = e.Error;
void Given(DealerManifestDownloadFailed e) => _pendingDealerIds.Remove(e.DealerId);
static Id Route(DealerManifestDownloadFailed e) => e.DealerId;