[HttpClient] Unit test for retries (#3730)

test/OpenTelemetry.Instrumentation.Http.Tests/HttpClientTests.Basic.cs

@@ -15,6 +15,7 @@
 // </copyright>
 #if !NETFRAMEWORK
 using System;
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
 using System.Net.Http;
@@ -300,30 +301,36 @@ namespace OpenTelemetry.Instrumentation.Http.Tests
             Assert.IsType<Activity>(processor.Invocations[1].Arguments[0]);
         }
 
-        [Fact]
-        public async Task HttpClientInstrumentationBacksOffIfAlreadyInstrumented()
+        [Fact(Skip = "https://github.com/open-telemetry/opentelemetry-dotnet/issues/3729")]
+        public async Task HttpClientInstrumentationExportsSpansCreatedForRetries()
         {
-            // TODO: Investigate why this feature is required.
-            var processor = new Mock<BaseProcessor<Activity>>();
-
+            var exportedItems = new List<Activity>();
             var request = new HttpRequestMessage
             {
                 RequestUri = new Uri(this.url),
                 Method = new HttpMethod("GET"),
             };
 
-            request.Headers.Add("traceparent", "00-0123456789abcdef0123456789abcdef-0123456789abcdef-01");
-
-            using (Sdk.CreateTracerProviderBuilder()
+            using var traceprovider = Sdk.CreateTracerProviderBuilder()
                    .AddHttpClientInstrumentation()
-                   .AddProcessor(processor.Object)
-                   .Build())
-            {
-                using var c = new HttpClient();
-                await c.SendAsync(request);
-            }
+                   .AddInMemoryExporter(exportedItems)
+                   .Build();
 
-            Assert.Equal(4, processor.Invocations.Count); // SetParentProvider/OnShutdown/Dispose/OnStart called.
+            int maxRetries = 3;
+            using var c = new HttpClient(new RetryHandler(new HttpClientHandler(), maxRetries));
+            await c.SendAsync(request);
+
+            // number of exported spans should be 3(maxRetries)
+            Assert.Equal(3, exportedItems.Count());
+
+            var spanid1 = exportedItems[0].SpanId;
+            var spanid2 = exportedItems[1].SpanId;
+            var spanid3 = exportedItems[2].SpanId;
+
+            // Validate span ids are different
+            Assert.NotEqual(spanid1, spanid2);
+            Assert.NotEqual(spanid3, spanid1);
+            Assert.NotEqual(spanid2, spanid3);
         }
 
         [Fact]

test/OpenTelemetry.Instrumentation.Http.Tests/RetryHandler.cs

@@ -0,0 +1,52 @@
+// <copyright file="RetryHandler.cs" company="OpenTelemetry Authors">
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace OpenTelemetry.Tests
+{
+    public class RetryHandler : DelegatingHandler
+    {
+        private int maxRetries;
+
+        public RetryHandler(HttpMessageHandler innerHandler, int maxRetries)
+            : base(innerHandler)
+        {
+            this.maxRetries = maxRetries;
+        }
+
+        protected override async Task<HttpResponseMessage> SendAsync(
+            HttpRequestMessage request,
+            CancellationToken cancellationToken)
+        {
+            HttpResponseMessage response = null;
+            for (int i = 0; i < this.maxRetries; i++)
+            {
+                try
+                {
+                    response = await base.SendAsync(request, cancellationToken);
+                }
+                catch
+                {
+                }
+            }
+
+            return response;
+        }
+    }
+}