Mocking HttpClient in unit tests

HttpClient’s extensibility lies in the HttpMessageHandler passed to the constructor. Its intent is to allow platform specific implementations, but you can also mock it. There’s no need to create a decorator wrapper for HttpClient.

If you’d prefer a DSL to using Moq, I have a library up on GitHub/Nuget that makes things a little easier: https://github.com/richardszalay/mockhttp

The Nuget Package RichardSzalay.MockHttp is available here.

var mockHttp = new MockHttpMessageHandler();

// Setup a respond for the user api (including a wildcard in the URL)
mockHttp.When("http://localost/api/user/*")
        .Respond("application/json", "{'name' : 'Test McGee'}"); // Respond with JSON

// Inject the handler or client into your application code
var client = new HttpClient(mockHttp);

var response = await client.GetAsync("http://localhost/api/user/1234");
// or without async: var response = client.GetAsync("http://localhost/api/user/1234").Result;

var json = await response.Content.ReadAsStringAsync();

// No network connection required
Console.Write(json); // {'name' : 'Test McGee'}