The roles of testing and monitoring often intersect yet maintain distinct identities due to their purpose and scope. E2E tests simulate user interactions to validate code correctness, while synthetic monitoring focuses on ensuring infrastructure health and user experience. The execution cost and frequency of these tests differ significantly, with E2E tests being resource-intensive and time-consuming, whereas synthetic tests are quick to run and provide timely feedback. The environment in which these tests operate also sets them apart, with E2E tests confined to isolated environments and synthetic monitoring mirroring real user behavior in the production environment. Differences in test design, such as tolerance for noise, also exist between testing and monitoring. However, there is a philosophical kinship between testing and monitoring, both involving observing software behavior, albeit passively versus actively. Integrating pre-production tests with synthetic monitoring can bring valuable insights into real-world performance and system health, while ensuring the smooth functioning of live environments. Embracing synergy between testing and monitoring can lead to a more robust and efficient software lifecycle, ensuring applications are well-tested and consistently monitored for optimal performance.