api-contract-testing

What it does

This skill automates the verification of API contracts by generating test cases and validating responses against expected schemas. It ensures that your backend services adhere to defined specifications before integration, catching breaking changes early in the development cycle.

When to use it

• You need to validate that a new API endpoint returns data matching a specific JSON schema.
• Your team is refactoring an existing service and you must ensure backward compatibility with current clients.
• You want to generate automated regression tests for an OpenAPI or Swagger definition without writing manual code.
• You are integrating third-party services and need to verify their actual behavior matches the documented contract.

Key capabilities

• Automatically generates test cases based on provided API documentation or schemas.
• Validates API responses against expected structures and data types.
• Identifies discrepancies between actual service behavior and defined contracts.
• Supports various common API specification formats for broad compatibility.

Example prompts

• "Generate a set of unit tests for this OpenAPI 3.0 specification to verify the /users endpoint returns valid JSON."
• "Check if the current implementation of the payment API matches the provided contract and list any breaking changes found."
• "Create validation rules to ensure the response from the inventory service adheres to the defined schema constraints."

Tips & gotchas

Ensure your API documentation is up-to-date, as the skill relies heavily on accurate definitions to generate meaningful tests. This tool complements but does not replace full end-to-end integration testing; it focuses specifically on contract adherence rather than business logic or external dependencies.