TestClient.cs

namespace Integration.Tests
{
    using System;
    using System.Net.Http;

    using Carter;

    using Microsoft.AspNetCore;
    using Microsoft.AspNetCore.Builder;
    using Microsoft.AspNetCore.Hosting;
    using Microsoft.AspNetCore.TestHost;
    using Microsoft.Extensions.DependencyInjection;

    public static class TestClient
    {
        public static HttpClient With(Action<IServiceCollection> addDependencies)
        {
            var server = new TestServer(
                WebHost.CreateDefaultBuilder()
                    .ConfigureServices(
                        services =>
                            {
                                addDependencies(services);
                                services.AddCarter();
                            })
                    .Configure(app =>
                        {
                            app.UseCarter();
                        }));

            var client = server.CreateClient();

            return client;
        }
    }
}