API Contract Testing

Overview

Turn an API change into explicit provider and consumer checks. Start from the actual contract and affected clients, then verify wire-level behavior rather than relying on generated types or a successful build. Default to local fixtures and existing test tools; this skill does not provision a testing service.

When to Use

• A response field, endpoint, event schema or error envelope changes.
• A client and server build successfully but disagree at runtime.
• A team needs to distinguish a breaking change from a compatible extension.
• A reported regression needs a minimal provider/consumer reproduction.

Do not use this as authorization to call production endpoints, bypass access controls or publish a new API version.

How It Works

1. Bind the contract and scope