Add oveload to CreateClient for adding extra handlers. (#164)

Author: dnperfors

CHANGELOG.md

@@ -4,6 +4,11 @@ All notable changes to TestableHttpClient will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), and 
 this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.8] - Unplanned
+
+### Added
+- `CreateClient` now accepts `DelegateHandlers` in order to chain Handlers. The InnerHandler property of each handler is set automatically and the `TestableHttpMessageHandler` is automatically set as the last handler. This is showcased with Polly in the integration tests.
+
 ## [0.7] - 2022-09-22
 ### Changed
 - In 0.6 the debug symbols were embedded in the dll, so the pipeline couldn't upload the symbol package. This is corrected in 0.7 where the symbol package is correct.
@@ -207,6 +212,7 @@ this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Automatically build project when pushing changes to github and when creating a pull request
 - Automatically deploy to NuGet when creating a tag in github
 
+[0.7]: https://github.com/dnperfors/TestableHttpClient/compare/v0.6...v0.7
 [0.6]: https://github.com/dnperfors/TestableHttpClient/compare/v0.5...v0.6
 [0.5]: https://github.com/dnperfors/TestableHttpClient/compare/v0.4...v0.5
 [0.4]: https://github.com/dnperfors/TestableHttpClient/compare/v0.3...v0.4

TestableHttpClient.sln

@@ -1,7 +1,7 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
-# Visual Studio Version 16
-VisualStudioVersion = 16.0.29709.97
+# Visual Studio Version 17
+VisualStudioVersion = 17.3.32901.215
 MinimumVisualStudioVersion = 15.0.26124.0
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{4C8914F8-D732-462B-978E-3BB5DBE547D7}"
 EndProject
@@ -17,6 +17,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution
 		CHANGELOG.md = CHANGELOG.md
 		LICENSE = LICENSE
 		README.md = README.md
+		version.json = version.json
 	EndProjectSection
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "TestableHttpClient.IntegrationTests", "test\TestableHttpClient.IntegrationTests\TestableHttpClient.IntegrationTests.csproj", "{37A6C1C0-1117-43DE-BD15-290BC8AD32BE}"

src/TestableHttpClient/AssertionMethodAttribute.cs

@@ -0,0 +1,4 @@
+namespace TestableHttpClient;
+
+[AttributeUsage(AttributeTargets.Method)]
+internal sealed class AssertionMethodAttribute : Attribute { }

src/TestableHttpClient/HttpRequestMessageAsserter.cs

@@ -43,6 +43,7 @@ private void Assert(int? expectedCount = null)
     /// <param name="requestFilter">The filter to filter requests with before asserting.</param>
     /// <param name="condition">The name of the conditon, used in the exception message.</param>
     /// <returns>The <seealso cref="IHttpRequestMessagesCheck"/> for further assertions.</returns>
+    [AssertionMethod]
     public IHttpRequestMessagesCheck WithFilter(Func<HttpRequestMessage, bool> requestFilter, string condition) => WithFilter(requestFilter, null, condition);
 
     /// <summary>
@@ -51,8 +52,10 @@ private void Assert(int? expectedCount = null)
     /// <param name="requestFilter">The filter to filter requests with before asserting.</param>
     /// <param name="condition">The name of the conditon, used in the exception message.</param>
     /// <returns>The <seealso cref="IHttpRequestMessagesCheck"/> for further assertions.</returns>
+    [AssertionMethod]
     public IHttpRequestMessagesCheck WithFilter(Func<HttpRequestMessage, bool> requestFilter, int expectedNumberOfRequests, string condition) => WithFilter(requestFilter, (int?)expectedNumberOfRequests, condition);
 
+    [AssertionMethod]
     public IHttpRequestMessagesCheck WithFilter(Func<HttpRequestMessage, bool> requestFilter, int? expectedNumberOfRequests, string condition)
     {
         if (!string.IsNullOrEmpty(condition))

src/TestableHttpClient/TestableHttpMessageHandler.cs

@@ -34,7 +34,7 @@ protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage reques
             {
                 cancelationSource.Cancel(false);
             }
-            throw new TaskCanceledException(new OperationCanceledException().Message);
+            return Task.FromCanceled<HttpResponseMessage>(cancellationToken);
         }
 
         return Task.FromResult(response);

src/TestableHttpClient/TestableHttpMessageHandlerAssertionExtensions.cs

@@ -9,6 +9,7 @@ public static class TestableHttpMessageHandlerAssertionExtensions
     /// <returns>An <see cref="IHttpRequestMessagesCheck"/> that can be used for additional assertions.</returns>
     /// <exception cref="ArgumentNullException">handler is `null`</exception>
     /// <exception cref="HttpRequestMessageAssertionException">When no requests are made</exception>
+    [AssertionMethod]
     public static IHttpRequestMessagesCheck ShouldHaveMadeRequests(this TestableHttpMessageHandler handler)
     {
         if (handler == null)
@@ -27,6 +28,7 @@ public static IHttpRequestMessagesCheck ShouldHaveMadeRequests(this TestableHttp
     /// <returns>An <see cref="IHttpRequestMessagesCheck"/> that can be used for additional assertions.</returns>
     /// <exception cref="ArgumentNullException">handler is `null`</exception>
     /// <exception cref="HttpRequestMessageAssertionException">When no requests are made</exception>
+    [AssertionMethod]
     public static IHttpRequestMessagesCheck ShouldHaveMadeRequests(this TestableHttpMessageHandler handler, int expectedNumberOfRequests)
     {
         if (handler == null)
@@ -45,6 +47,7 @@ public static IHttpRequestMessagesCheck ShouldHaveMadeRequests(this TestableHttp
     /// <returns>An <see cref="IHttpRequestMessagesCheck"/> that can be used for additional assertions.</returns>
     /// <exception cref="ArgumentNullException">handler is `null` or pattern is `null`</exception>
     /// <exception cref="HttpRequestMessageAssertionException">When no requests are made</exception>
+    [AssertionMethod]
     public static IHttpRequestMessagesCheck ShouldHaveMadeRequestsTo(this TestableHttpMessageHandler handler, string pattern)
     {
         if (handler == null)
@@ -69,6 +72,7 @@ public static IHttpRequestMessagesCheck ShouldHaveMadeRequestsTo(this TestableHt
     /// <returns>An <see cref="IHttpRequestMessagesCheck"/> that can be used for additional assertions.</returns>
     /// <exception cref="ArgumentNullException">handler is `null` or pattern is `null`</exception>
     /// <exception cref="HttpRequestMessageAssertionException">When no requests are made</exception>
+    [AssertionMethod]
     public static IHttpRequestMessagesCheck ShouldHaveMadeRequestsTo(this TestableHttpMessageHandler handler, string pattern, int expectedNumberOfRequests)
     {
         if (handler == null)

src/TestableHttpClient/TestableHttpMessageHandlerExtensions.cs

@@ -9,9 +9,9 @@ public static class TestableHttpMessageHandlerExtensions
     /// <returns>An HttpClient configure with the TestableHttpMessageHandler.</returns>
     /// <exception cref="ArgumentNullException">The `handler` is `null`</exception>
     /// <remarks>Using this method is equivalent to `new HttClient(handler)`.</remarks>
-    public static HttpClient CreateClient(this TestableHttpMessageHandler handler)
+    public static HttpClient CreateClient(this TestableHttpMessageHandler handler, params DelegatingHandler[] httpMessageHandlers)
     {
-        return CreateClient(handler, _ => { });
+        return CreateClient(handler, _ => { }, httpMessageHandlers);
     }
 
     /// <summary>
@@ -22,6 +22,11 @@ public static HttpClient CreateClient(this TestableHttpMessageHandler handler)
     /// <returns>An HttpClient configure with the TestableHttpMessageHandler.</returns>
     /// <exception cref="ArgumentNullException">The `handler` or `configureClient` is `null`</exception>
     public static HttpClient CreateClient(this TestableHttpMessageHandler handler, Action<HttpClient> configureClient)
+    {
+        return CreateClient(handler, configureClient, Enumerable.Empty<DelegatingHandler>());
+    }
+
+    public static HttpClient CreateClient(this TestableHttpMessageHandler handler, Action<HttpClient> configureClient, IEnumerable<DelegatingHandler> httpMessageHandlers)
     {
         if (handler is null)
         {
@@ -33,9 +38,31 @@ public static HttpClient CreateClient(this TestableHttpMessageHandler handler, A
             throw new ArgumentNullException(nameof(configureClient));
         }
 
-        var httpClient = new HttpClient(handler);
+        if (httpMessageHandlers is null)
+        {
+            throw new ArgumentNullException(nameof(httpMessageHandlers));
+        }
+
+        if (httpMessageHandlers.Any(x => x is null))
+        {
+            throw new ArgumentNullException(nameof(httpMessageHandlers));
+        }
+
+        var httpClient = new HttpClient(CreateHandlerChain(handler, httpMessageHandlers));
         configureClient(httpClient);
 
         return httpClient;
     }
+
+    private static HttpMessageHandler CreateHandlerChain(TestableHttpMessageHandler handler, IEnumerable<DelegatingHandler> additionalHandlers)
+    {
+        HttpMessageHandler next = handler;
+        var reversedHandlers = additionalHandlers.Reverse();
+        foreach (var delegatingHandler in reversedHandlers)
+        {
+            delegatingHandler.InnerHandler = next;
+            next = delegatingHandler;
+        }
+        return next;
+    }
 }

test/TestableHttpClient.IntegrationTests/TestableHttpClient.IntegrationTests.csproj

@@ -7,11 +7,13 @@
   <ItemGroup Condition="'$(TargetFramework)' == 'netcoreapp3.1'">
     <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="[3.1.*,5.0.0)" />
     <PackageReference Include="Microsoft.Extensions.Http" Version="[3.1.*,5.0.0)" />
+    <PackageReference Include="Microsoft.Extensions.Http.Polly" Version="[3.1.*,5.0.0)" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFramework)' == 'net6.0'">
     <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="[6.0.*,)" />
     <PackageReference Include="Microsoft.Extensions.Http" Version="[6.0.*,)" />
+    <PackageReference Include="Microsoft.Extensions.Http.Polly" Version="[6.0.*,)" />
   </ItemGroup>
 
   <ItemGroup>

test/TestableHttpClient.IntegrationTests/TestingRetryMechanisms.cs

@@ -0,0 +1,56 @@
+using Microsoft.Extensions.Http;
+
+using Polly;
+using Polly.Extensions.Http;
+
+namespace TestableHttpClient.IntegrationTests;
+
+public class TestingRetryMechanisms
+{
+    [Fact]
+    public async Task TestingRetryPolicies()
+    {
+        // Create TestableHttpMessageHandler as usual.
+        using var testableHttpMessageHandler = new TestableHttpMessageHandler();
+        testableHttpMessageHandler.RespondWith(response => response.WithHttpStatusCode(HttpStatusCode.ServiceUnavailable));
+
+        // Configure the retry policy
+        var policy = HttpPolicyExtensions.HandleTransientHttpError().RetryAsync(2);
+        using PolicyHttpMessageHandler retryPolicyHandler = new(policy);
+
+        using HttpClient client = testableHttpMessageHandler.CreateClient(retryPolicyHandler);
+
+        // Make a request, which should fail
+        _ = await client.GetAsync("https://httpbin.com/get");
+
+        // Now use the assertions to make sure the request was actually made multiple times.
+        testableHttpMessageHandler.ShouldHaveMadeRequestsTo("https://httpbin.com/get", 3);
+    }
+
+    [Fact]
+    public async Task SimulateTimeoutDoesNotRetry()
+    {
+        // Create TestableHttpMessageHandler as usual.
+        using var testableHttpMessageHandler = new TestableHttpMessageHandler();
+        testableHttpMessageHandler.SimulateTimeout();
+
+        // Configure the retry policy
+        var policy = HttpPolicyExtensions.HandleTransientHttpError().RetryAsync(2);
+        using PolicyHttpMessageHandler retryPolicyHandler = new(policy);
+
+        using HttpClient client = testableHttpMessageHandler.CreateClient(retryPolicyHandler);
+
+        try
+        {
+            _ = await client.GetAsync("https://httpbin.com/get");
+            Assert.Fail("This should never be reached, since a timeout should throw an exception.");
+        }
+        catch (TaskCanceledException)
+        {
+            // Catch the TaskCanceledException, since we know we that is thrown when a timeout occurs
+        }
+
+        // Now use the assertions to make sure the request was actually made once, so polly didn't run.
+        testableHttpMessageHandler.ShouldHaveMadeRequestsTo("https://httpbin.com/get", 1);
+    }
+}

test/TestableHttpClient.Tests/TestableHttpMessageHandlerExtensionsTests/CreateClient.cs

@@ -4,16 +4,14 @@ namespace TestableHttpClient.Tests;
 
 public partial class TestableHttpMessageHandlerExtensionsTests
 {
-#nullable disable
     [Fact]
     public void CreateClient_NullTestableHttpMessageHandler_ThrowsArgumentNullException()
     {
-        TestableHttpMessageHandler sut = null;
+        TestableHttpMessageHandler sut = null!;
 
         var exception = Assert.Throws<ArgumentNullException>(() => sut.CreateClient());
         Assert.Equal("handler", exception.ParamName);
     }
-#nullable restore
 
     [Fact]
     public void CreateClient_CorrectTestableHttpMessageHandler_AddsHandlerToHttpClient()
@@ -27,14 +25,23 @@ public void CreateClient_CorrectTestableHttpMessageHandler_AddsHandlerToHttpClie
         Assert.Same(sut, handler);
     }
 
-    private static object? GetPrivateHandler(HttpClient client)
+    [Fact]
+    public void CreateClient_NullDelegateHandler_ThrowsArgumentNullException()
+    {
+        using TestableHttpMessageHandler sut = new();
+        DelegatingHandler handler = null!;
+        var exception = Assert.Throws<ArgumentNullException>(() => sut.CreateClient(handler));
+        Assert.Equal("httpMessageHandlers", exception.ParamName);
+    }
+
+    private static HttpMessageHandler? GetPrivateHandler(HttpClient client)
     {
         var handlerField = client.GetType().BaseType?.GetField("_handler", BindingFlags.Instance | BindingFlags.NonPublic);
         if (handlerField == null)
         {
             Assert.True(false, "Can't find the private _handler field on HttpClient.");
             return null;
         }
-        return handlerField.GetValue(client);
+        return handlerField.GetValue(client) as HttpMessageHandler;
     }
 }