Independent service deployments break the core assumption of conventional regression testing: that mocks and test suites evolve in lockstep with the system. In microservice architectures where services deploy on their own schedules, static mocks drift from reality silently — passing tests while production behavior diverges. Contract testing (Pact) helps but requires both sides to participate, and manual mock maintenance processes don't scale past ~10-20 services deploying frequently. Modern traffic-based tools like Keploy address the root cause by deriving test coverage from observed real behavior rather than manually authored specifications, keeping cross-service assumptions current automatically. The two approaches are complementary: Pact catches breaking changes proactively at the provider pipeline, while traffic-capture tools keep consumer-side mocks current continuously.
