wasmo

https://github.com/conao3/wasm-wasmo

wasmo runs a stateful AWS mock inside the test process. A Seahorse plugin replaces the HTTP send handler of the AWS SDK for Ruby v3 and answers every request from a WebAssembly module run with wasmtime-rb, so signing, retries, checksums, and response parsing stay in the SDK. Each mock owns an isolated instance, with no Docker, ports, or sidecar process.