Conformance suite

Prove an implementation speaks FedNow Service Release 1 — in either direction.

Three tools

1. The vector corpus (vectors/) — language-agnostic test vectors: real ISO 20022 messages (valid and deliberately broken) with expected verdicts in vectors/manifest.toml. Any implementation, in any language, can consume the XML and assert the valid field; implementations adopting fednow-core’s rule taxonomy also assert the exact codes (e.g. fednow.aba.checksum). Run it against fednow-core itself:

cargo run -p fednow-conformance -- vectors

2. The validator — judge any message file or directory against the FedNow Release 1 profiles (message type detected from the namespace):

cargo run -p fednow-conformance -- validate path/to/messages/

3. The scenario runner — drive a live FedNow-Service-side endpoint through the official Customer Testing Program credit-transfer scenarios (Readiness Portal Guide, chapter 3) and report pass/fail:

cargo run -p fednow-sim &          # or any implementation of the same contract
cargo run -p fednow-conformance -- scenarios http://localhost:8080
# PASS cct-1-happy-path
# PASS cct-2-service-reject
# PASS cct-3-participant-reject
# PASS cct-4-accept-without-posting
# PASS cct-5-timeout-then-query
# PASS cct-6-query-unknown-is-not-found

fednow-sim passes all scenarios in CI — the suite keeps the simulator honest and gives anyone building against it a certification target before the real Customer Testing Program.

Claiming conformance

An implementation may claim “message-conformant with fednow-core vX” when it agrees with every vector’s valid verdict, and “scenario-conformant” when the scenario runner passes against it. Both checks are deterministic and run in one command.