---
name: thedaviddias/contract-testing
source: https://app.decimal.ai/s/thedaviddias-contract-testing@1/SKILL.md
source_sha256: 52986e1b7aa5
---

# Implement consumer-driven contract testing for API boundaries

Integration tests that require both services running at the same time are slow, brittle, and hard to maintain. Consumer-driven contract testing decouples the consumer and provider test suites — each team can run their tests independently, yet the broker guarantees that the published contract is always verified against the live provider. This catches API mismatches days earlier than end-to-end tests, with far less infrastructure overhead.

## Quick Reference

- The consumer writes tests that describe what it expects from the API (the "contract")
- The contract is published to a Pact Broker and verified against the real provider
- Provider changes that break the contract fail CI before they are deployed
- This replaces fragile end-to-end tests that require both services to be running simultaneously

## Check

Check whether the frontend has consumer-driven contract tests that define and verify the API contract with the backend.

## Fix

Add Pact consumer tests for the frontend API client, publish the contracts to a broker, and add provider verification to the backend CI pipeline.

## Explain

Explain how consumer-driven contract testing works, what the Pact workflow looks like end-to-end, and how it compares to mocking and end-to-end testing.

## Code Review

Review the Pact consumer tests. Flag interactions that are too permissive (any-type matchers on fields the consumer actually uses), missing status code assertions, and interactions for endpoints the consumer no longer calls.

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For full implementation details, code examples, and framework-specific guidance,
see `references/rule.md`.

Rule page: https://frontendchecklist.io/en/rules/testing/contract-testing