Meziantou.Framework

Introduction

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Meziantou.Framework.HttpClientMock provides HttpClientMock, a mock HTTP server for testing code that uses HttpClient. You describe the responses with the same handlers as in an ASP.NET Core minimal API (MapGet, MapPost, Results.Ok, route parameters, parameter binding), and the mock gives you an HttpClient or an HttpMessageHandler that sends the requests to it.

The mock runs an ASP.NET Core application on the in-memory test server (Microsoft.AspNetCore.TestHost): no port is opened and no request leaves the process, unless you ask the mock to forward it.

What you can do with it

  • Mock an HTTP service and get an HttpClient that calls it. See Getting started.
  • Match requests by method, path, route parameters, query string, scheme, host and port. See Matching requests.
  • Return responses: objects serialized as JSON, raw JSON or XML, status codes, headers, responses computed from the request; or forward requests to the real service. See Responses.
  • Verify the calls the code under test made: count them, capture what was sent, and return a different response on each call. See Verifying calls.
  • Replace the clients of IHttpClientFactory in a service collection: the default client, named clients and typed clients, and fail on any client you forgot to mock. See Dependency injection.
  • Configure the mock: logging to the test output, services and configuration of the mock's application. See Logging and services.

When to use it

Use HttpClientMock when a test needs to decide what the remote service answers: an error, a timeout-prone endpoint that fails once, an edge case that the real service rarely returns. The handlers are code, so a response can depend on the request or on the calls made before.

When you would rather replay what the real service answered, record the traffic once and replay it with HTTP recording. The other HTTP packages of this repository, such as caching or HSTS handlers, are described in the Http section.

Namespace

HttpClientMock, RequestCounter, HttpMockServiceBuilder and the extension methods of the package are in the Meziantou.Framework namespace. The handlers use the ASP.NET Core types of Microsoft.AspNetCore.Http, such as Results and HttpContext.

Next steps