What problem does it solve? Testing code that calls an APIMatic-generated .NET SDK is tricky because the SDK ships no mocking helpers, and naive tests either hit the real network or assert SDK internals instead of real behaviour. This Skill shows how to use the HttpClient constructor seam to fake HTTP responses and write meaningful tests. ## Core Features & Use Cases - HttpMessageHandler test seam: Build a reusable StubHandler that captures every request and returns canned responses, so no real network calls happen. - Error and result-path coverage: Assert typed SdkException<{Operation}Error> or SdkException<RawError> on failure paths, and test the non-throwing ApiResult variant directly. - Request and retry assertions: Verify outgoing method, path, query, and body, plus retry behaviour for status faults versus transport faults and write-once guarantees. - Use Case: You are writing integration-layer tests for a C# service that calls a generated SDK client. Use this Skill to stub a 422 response, assert the typed error is thrown, and confirm the outgoing POST body contains the expected fields. ## Quick Start Ask your AI agent to write xUnit tests for the code calling your APIMatic .NET SDK using a stubbed HttpMessageHandler, covering success, error, and retry paths.
