Case Study: Stitch Fix improves event-driven contract testing with Serverless Framework

Stitch Fix validates event-driven contracts with Serverless Inc in a 5-hour prototype

Stitch Fix, an e-commerce personal styling service, faced a challenge ensuring their complex, event-driven architecture remained reliable as different engineering teams independently updated their own systems. Their warehouse management system, which generates packing slips, depended on synchronous calls and asynchronous messages from other services. A change in one service could silently break the core business process. Serverless Inc is the vendor hosting this conference talk where the Director of Engineering from Stitch Fix presented their innovative approach to this problem.

The solution, explored by Stitch Fix with insights from Serverless Inc, was to implement a form of contract-based testing for their messaging system. This involved creating a central authority to manage "guarantees" from message producers and "expectations" from consumers. A proof-of-concept was built to automatically verify that messages conformed to required schemas, preventing breaking changes from being deployed. This provided increased confidence that inter-service communications would work correctly in production, preventing potential failures that would be difficult to detect otherwise.

Stitch Fix