Add new Polly DI extension method for HttpClientFactory (#28283)

* Fix IDE warnings

Fix IDE warnings about non-disposed handlers.

* Update return type documentation

Update the comment's type to match the method's.

* Add new AddPolicyRegistry overload

Add a new overload for AddPolicyRegistry() that allows the
caller to configure the policy registry using other services
that are registered with the service provider, such as config.

Author: martincostello

src/HttpClientFactory/Polly/src/DependencyInjection/PollyServiceCollectionExtensions.cs

@@ -8,7 +8,7 @@
 namespace Microsoft.Extensions.DependencyInjection
 {
     /// <summary>
-   /// Provides convenience extension methods to register <see cref="IPolicyRegistry{String}"/> and 
+   /// Provides convenience extension methods to register <see cref="IPolicyRegistry{String}"/> and
    /// <see cref="IReadOnlyPolicyRegistry{String}"/> in the service collection.
     /// </summary>
     public static class PollyServiceCollectionExtensions
@@ -19,15 +19,15 @@ public static class PollyServiceCollectionExtensions
         /// the newly created registry.
         /// </summary>
         /// <param name="services">The <see cref="IServiceCollection"/>.</param>
-        /// <returns>The newly created <see cref="PolicyRegistry"/>.</returns>
+        /// <returns>The newly created <see cref="IPolicyRegistry{String}"/>.</returns>
         public static IPolicyRegistry<string> AddPolicyRegistry(this IServiceCollection services)
         {
             if (services == null)
             {
                 throw new ArgumentNullException(nameof(services));
             }
 
-            // Create an empty registry, register and return it as an instance. This is the best way to get a 
+            // Create an empty registry, register and return it as an instance. This is the best way to get a
             // single instance registered using both interfaces.
             var registry = new PolicyRegistry();
             services.AddSingleton<IPolicyRegistry<string>>(registry);
@@ -61,5 +61,42 @@ public static IPolicyRegistry<string> AddPolicyRegistry(this IServiceCollection
 
             return registry;
         }
+
+        /// <summary>
+        /// Registers an empty <see cref="PolicyRegistry"/> in the service collection with service types
+        /// <see cref="IPolicyRegistry{String}"/>, and <see cref="IReadOnlyPolicyRegistry{String}"/> and
+        /// uses the specified delegate to configure it.
+        /// </summary>
+        /// <param name="services">The <see cref="IServiceCollection"/>.</param>
+        /// <param name="configureRegistry">A delegate that is used to configure an <see cref="IPolicyRegistry{String}"/>.</param>
+        /// <returns>The provided <see cref="IServiceCollection"/>.</returns>
+        public static IServiceCollection AddPolicyRegistry(this IServiceCollection services, Action<IServiceProvider, IPolicyRegistry<string>> configureRegistry)
+        {
+            if (services == null)
+            {
+                throw new ArgumentNullException(nameof(services));
+            }
+
+            if (configureRegistry == null)
+            {
+                throw new ArgumentNullException(nameof(configureRegistry));
+            }
+
+            // Create an empty registry, configure it and register it as an instance.
+            // This is the best way to get a single instance registered using both interfaces.
+            services.AddSingleton(serviceProvider =>
+            {
+                var registry = new PolicyRegistry();
+
+                configureRegistry(serviceProvider, registry);
+
+                return registry;
+            });
+
+            services.AddSingleton<IPolicyRegistry<string>>(serviceProvider => serviceProvider.GetRequiredService<PolicyRegistry>());
+            services.AddSingleton<IReadOnlyPolicyRegistry<string>>(serviceProvider => serviceProvider.GetRequiredService<PolicyRegistry>());
+
+            return services;
+        }
     }
 }

src/HttpClientFactory/Polly/src/PublicAPI.Unshipped.txt

@@ -1 +1,2 @@
 #nullable enable
+~static Microsoft.Extensions.DependencyInjection.PollyServiceCollectionExtensions.AddPolicyRegistry(this Microsoft.Extensions.DependencyInjection.IServiceCollection services, System.Action<System.IServiceProvider, Polly.Registry.IPolicyRegistry<string>> configureRegistry) -> Microsoft.Extensions.DependencyInjection.IServiceCollection

src/HttpClientFactory/Polly/test/DependencyInjection/PollyHttpClientBuilderExtensionsTest.cs

@@ -31,7 +31,7 @@ public PollyHttpClientBuilderExtensionsTest()
         // Allows the exception from our handler to propegate
         private IAsyncPolicy<HttpResponseMessage> NoOpPolicy { get; }
 
-        // Matches what our client handler does 
+        // Matches what our client handler does
         private IAsyncPolicy<HttpResponseMessage> RetryPolicy { get; }
 
         [Fact]
@@ -255,7 +255,7 @@ public async Task AddPolicyHandlerFromRegistry_Dynamic_AddsPolicyHandler()
         public async Task AddTransientHttpErrorPolicy_AddsPolicyHandler_HandlesStatusCode(HttpStatusCode statusCode)
         {
             // Arrange
-            var handler = new SequenceMessageHandler()
+            using var handler = new SequenceMessageHandler()
             {
                 Responses =
                 {
@@ -303,7 +303,7 @@ public async Task AddTransientHttpErrorPolicy_AddsPolicyHandler_HandlesStatusCod
         public async Task AddTransientHttpErrorPolicy_AddsPolicyHandler_HandlesHttpRequestException()
         {
             // Arrange
-            var handler = new SequenceMessageHandler()
+            using var handler = new SequenceMessageHandler()
             {
                 Responses =
                 {
@@ -415,6 +415,59 @@ public async Task AddPolicyHandlerFromRegistry_PolicySelectorWithKey_AddsPolicyH
             Assert.True(registry.ContainsKey("host2"));
         }
 
+        [Fact]
+        public async Task AddPolicyHandlerFromRegistry_WithConfigureDelegate_AddsPolicyHandler()
+        {
+            var options = new PollyPolicyOptions()
+            {
+                PolicyName = "retrypolicy"
+            };
+
+            var serviceCollection = new ServiceCollection();
+
+            serviceCollection.AddSingleton(options);
+
+            serviceCollection.AddPolicyRegistry((serviceProvider, registry) =>
+            {
+                string policyName = serviceProvider.GetRequiredService<PollyPolicyOptions>().PolicyName;
+
+                registry.Add<IAsyncPolicy<HttpResponseMessage>>(policyName, RetryPolicy);
+            });
+
+            HttpMessageHandlerBuilder builder = null;
+
+            // Act1
+            serviceCollection.AddHttpClient("example.com", c => c.BaseAddress = new Uri("http://example.com"))
+                .AddPolicyHandlerFromRegistry(options.PolicyName)
+                .ConfigureHttpMessageHandlerBuilder(b =>
+                {
+                    b.PrimaryHandler = PrimaryHandler;
+
+                    builder = b;
+                });
+
+            var services = serviceCollection.BuildServiceProvider();
+            var factory = services.GetRequiredService<IHttpClientFactory>();
+
+            // Act2
+            var client = factory.CreateClient("example.com");
+
+            // Assert
+            Assert.NotNull(client);
+
+            Assert.Collection(
+                builder.AdditionalHandlers,
+                h => Assert.IsType<LoggingScopeHttpMessageHandler>(h),
+                h => Assert.IsType<PolicyHttpMessageHandler>(h),
+                h => Assert.IsType<LoggingHttpMessageHandler>(h));
+
+            // Act 3
+            var response = await client.SendAsync(new HttpRequestMessage());
+
+            // Assert
+            Assert.Equal(HttpStatusCode.Created, response.StatusCode);
+        }
+
         // Throws an exception or fails on even numbered requests, otherwise succeeds.
         private class FaultyMessageHandler : DelegatingHandler
         {
@@ -447,5 +500,10 @@ protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage reques
                 return Task.FromResult(func(request));
             }
         }
+
+        private class PollyPolicyOptions
+        {
+            public string PolicyName { get; set; }
+        }
     }
 }