The advent of microservices architecture has led to significant changes in software testing, with a shift from monolithic testing to granular, simultaneous development and testing. Unit tests are essential for ensuring the basic functionality of individual services, while integration tests focus on communication between services and external components. Chaos engineering helps build resilient applications by inducing failures and forcing engineers to respond, but this practice should be started small and implemented with tools like Istio or Chaos Monkey. Finally, test automation is crucial for enabling successful GitOps, which automates deployments starting from a GitHub repository, and requires a keen focus on testing to maintain quality.