Contract Testing
Pact and OpenAPI both prevent API integration failures, but they solve different parts of the problem. OpenAPI defines the contract — the shape of requests and responses. Pact verifies that specific consumer interactions are honored by the provider. Used together, they cover each other's blind spots. This guide shows
API Testing
REST APIs have OpenAPI. Event-driven systems — Kafka topics, RabbitMQ queues, WebSocket channels — have AsyncAPI. If your microservices communicate via events and you're not validating message schemas, you're flying blind. A producer changes a field name, drops a required field, or changes a type. Every downstream
API Testing
Frontend development has a classic blocking problem: the backend isn't ready. You're building a checkout flow, but the payments API returns a 500. You want to test the empty state, but the backend always returns data. You need to simulate a 429 rate limit, but production
API Testing
You can't write a test for every possible input. A string field accepts billions of values. A numeric parameter has edge cases you haven't considered. An API that looks solid against your 20 hand-written test cases might crash on the 21st input — the one a
API Testing
Writing API tests by hand means writing a lot of boilerplate: constructing URLs, setting headers, serializing request bodies, parsing responses. When the API changes, you update the tests manually and hope you caught every callsite. OpenAPI Generator eliminates that boilerplate. Given an OpenAPI spec, it generates a fully typed API
API Testing
Both Dredd and Schemathesis test whether your API implementation matches its spec. Both read OpenAPI (or API Blueprint) definitions and make real HTTP requests. Beyond that, they take fundamentally different approaches — and understanding the difference determines which one belongs in your pipeline. The Core Difference Dredd is deterministic. It reads
API Testing
API contracts are promises. Your OpenAPI specification says "this endpoint returns a userId field of type string." Every consumer of your API — mobile apps, partner integrations, frontend teams — builds against that promise. When the promise breaks silently, you get production incidents, not compiler errors. Spectral is a linter
API Testing
Most teams write code first, then document it. The API exists; you write the OpenAPI spec to describe what you built. This approach has a persistent problem: the code and the documentation diverge. Consumers get specs that don't match the real behavior. Tests get written against the implementation,