isTestMode example

if ($event->isPropagationStopped()) {
            return null;
        }

        $definition = $this->getValidationDefinition($context);
        $this->dataValidator->validate($data, $definition);

        $recipients = $data['recipients'];
        $salesChannelId = $data['salesChannelId'];
        $salesChannel = null;

        if (($salesChannelId !== null && !isset($templateData['salesChannel'])) || $this->isTestMode($data)) {
            $criteria = $this->getSalesChannelDomainCriteria($salesChannelId, $context);

            /** @var SalesChannelEntity|null $salesChannel */
            $salesChannel = $this->salesChannelRepository->search($criteria, $context)->get($salesChannelId);

            if ($salesChannel === null) {
                throw new SalesChannelNotFoundException($salesChannelId);
            }

            $templateData['salesChannel'] = $salesChannel;
        } elseif ($this->templateDataContainsSalesChannel($templateData)) {