InfluxData developed a simulator called Gems to replicate the functionality of AWS Marketplace for testing purposes, eliminating the need for third-party resources in their original application. The Gems simulator mimics key services like REST API, Simple Notification Service (SNS), and Simple Queue Service (SQS) to ensure a similar user onboarding flow while testing with Quartz, without relying on AWS's infrastructure. This allows InfluxData to test their SaaS product more thoroughly and efficiently, preparing them for future integrations with other cloud services like GCP and Azure.