The author of this text, a MongoDB engineer, discusses the challenges of conformance checking in software development. Conformance checking involves testing that an implementation matches its specifications, which are often written in formal languages like TLA+. The author describes two approaches: trace-checking and test-case generation. Trace-checking starts with an implementation and checks if it conforms to a specification by generating execution traces and verifying that they match the spec's behavior. Test-case generation starts with a specification and generates tests to verify that the implementation follows its behaviors. The author shares their experience with these approaches, highlighting successes and failures, and discusses lessons learned. They also mention ongoing research in conformance checking techniques, including new tools and methods for improving the process. The goal of conformance checking is to ensure that code matches specifications, which is crucial for developing reliable and maintainable software systems.