Feature/expose http handlers (#224)

* temp commit

* trying to work out how to expose the http handlers in a decent way..

* pissing about at lunch

* changed to func so you can instanciate object or new it up each time

* docs for dele handlers

* upgraded to sdk 2.1.4

* some validation for consul services

test/Ocelot.UnitTests/Requester/HttpClientBuilderTests.cs

@@ -0,0 +1,114 @@
+using System;
+using System.Collections.Generic;
+using System.Net.Http;
+using Moq;
+using Ocelot.Requester;
+using Ocelot.Responses;
+using Shouldly;
+using TestStack.BDDfy;
+using Xunit;
+
+namespace Ocelot.UnitTests.Requester
+{
+    public class HttpClientBuilderTests
+    {
+        private readonly HttpClientBuilder _builder;
+        private readonly Mock<IDelegatingHandlerHandlerHouse> _house;
+        private readonly Mock<IDelegatingHandlerHandlerProvider> _provider;
+        private IHttpClientBuilder _builderResult;
+        private IHttpClient _httpClient;
+        private HttpResponseMessage _response;
+        private Ocelot.Request.Request _request;
+
+        public HttpClientBuilderTests()
+        {
+            _provider = new Mock<IDelegatingHandlerHandlerProvider>();
+            _house = new Mock<IDelegatingHandlerHandlerHouse>();
+            _builder = new HttpClientBuilder(_house.Object);
+        }
+
+        [Fact]
+        public void should_build_http_client()
+        {
+            this.Given(x => GivenTheProviderReturns())
+                .And(x => GivenARequest())
+                .And(x => GivenTheHouseReturns())
+                .When(x => WhenIBuild())
+                .Then(x => ThenTheHttpClientShouldNotBeNull())
+                .BDDfy();
+        }
+
+        [Fact]
+        public void should_call_delegating_handlers_in_order()
+        {
+            var fakeOne = new FakeDelegatingHandler();
+            var fakeTwo = new FakeDelegatingHandler();
+
+            var handlers = new List<Func<DelegatingHandler>>()
+            { 
+                () => fakeOne,
+                () => fakeTwo
+            };
+
+            this.Given(x => GivenTheProviderReturns(handlers))
+                .And(x => GivenARequest())
+                .And(x => GivenTheHouseReturns())
+                .And(x => WhenIBuild())
+                .When(x => WhenICallTheClient())
+                .Then(x => ThenTheFakeAreHandledInOrder(fakeOne, fakeTwo))
+                .And(x => ThenSomethingIsReturned())
+                .BDDfy();
+        }
+
+        private void GivenARequest()
+        {
+            _request = new Ocelot.Request.Request(null, false, null, false, false, "", false);
+        }
+
+        private void GivenTheHouseReturns()
+        {
+            _house
+                .Setup(x => x.Get(It.IsAny<Ocelot.Request.Request>()))
+                .Returns(new OkResponse<IDelegatingHandlerHandlerProvider>(_provider.Object));
+        }
+
+        private void ThenSomethingIsReturned()
+        {
+            _response.ShouldNotBeNull();
+        }
+
+        private void WhenICallTheClient()
+        {
+            _response = _httpClient.SendAsync(new HttpRequestMessage(HttpMethod.Get, "http://test.com")).GetAwaiter().GetResult();
+        }
+
+        private void ThenTheFakeAreHandledInOrder(FakeDelegatingHandler fakeOne, FakeDelegatingHandler fakeTwo)
+        {
+            fakeOne.TimeCalled.ShouldBeGreaterThan(fakeTwo.TimeCalled);
+        }
+
+        private void GivenTheProviderReturns()
+        {
+            _provider
+                .Setup(x => x.Get())
+                .Returns(new List<Func<DelegatingHandler>>(){ () => new FakeDelegatingHandler()});
+        }
+
+        private void GivenTheProviderReturns(List<Func<DelegatingHandler>> handlers)
+        {
+            _provider
+                .Setup(x => x.Get())
+                .Returns(handlers);
+        }
+
+        private void WhenIBuild()
+        {
+            _httpClient = _builder.Create(_request);
+        }
+
+        private void ThenTheHttpClientShouldNotBeNull()
+        {
+            _httpClient.ShouldNotBeNull();
+        }
+    }
+}