From REST to Events: API Workflow Testing and Mocking with a Single Arazzo Spec

APIs rarely work in isolation. Real-world usage involves multiple steps across both synchronous REST calls and asynchronous events, where the outcome of each step determines the journey a particular interaction takes. While testing individual endpoints is necessary, it’s not sufficient. It is equally important to validate how those endpoints and events work together as part of a real workflow.

Enter the Arazzo Specification V1.1, which describes complete workflows including inputs, outputs, step dependencies, and success/failure criteria, across OpenAPI (REST) and AsyncAPI (events). In this talk, we’ll demonstrate how you can leverage Arazzo to drive end-to-end API workflow testing and mocking in a completely no-code manner.

We’ll show how Arazzo + Specmatic enables shift-left testing of entire API journeys, spanning both sync and async operations. You’ll see how mocking complete workflows can unblock frontend teams, simulate event-driven flows, and accelerate CI pipelines. The session will also walk through the full lifecycle of how we design a multi-step journey, author or generate an Arazzo spec to capture it, and ensure both providers and consumers adhere to the same contract; thereby enabling independent, parallel development and deployment of services and components in complex, event-driven microservice architectures.