Only retry 500 errors within 500-504 range

Author: dylan-asos

src/SendGrid/Reliability/RetryDelegatingHandler.cs

@@ -78,7 +78,7 @@ protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage
 
         private static void ThrowHttpRequestExceptionIfResponseIsWithinTheServerErrorRange(HttpResponseMessage responseMessage)
         {
-            if ((int)responseMessage.StatusCode >= 500 && (int)responseMessage.StatusCode < 600)
+            if ((int)responseMessage.StatusCode >= 500 && (int)responseMessage.StatusCode <= 504)
             {
                 throw new HttpRequestException(string.Format("Response Http Status code {0} indicates server error", responseMessage.StatusCode));
             }

tests/SendGrid.Tests/Reliability/RetryDelegatingHandlerTests.cs

@@ -58,6 +58,17 @@ public async Task Invoke_ShouldReturnErrorWithoutRetryWhenErrorIsNotTransient()
             Assert.Equal(1, innerHandler.InvocationCount);
         }
 
+        [Fact]
+        public async Task Invoke_ShouldReturnErrorWithoutRetryWhen500ErrorStatusIsNotTransient()
+        {
+            innerHandler.AddBehaviour(innerHandler.HttpVersionNotSupported);
+
+            var response = await client.SendAsync(new HttpRequestMessage());
+
+            Assert.Equal((HttpStatusCode)505, response.StatusCode);
+            Assert.Equal(1, innerHandler.InvocationCount);
+        }
+
         [Fact]
         public async Task Invoke_ShoulddRetryOnceWhenFailedOnFirstAttemptThenSuccessful()
         {

tests/SendGrid.Tests/Reliability/RetryTestBehaviourDelegatingHandler.cs

@@ -31,19 +31,26 @@ Task<HttpResponseMessage> behaviour()
 
         public Task<HttpResponseMessage> OK()
         {
-            var httpResponseMessage = new HttpResponseMessage(HttpStatusCode.OK) { Content = new StringContent(string.Empty) };
-            return Task.Factory.StartNew(() => httpResponseMessage);
+            return CreateHttpResponse(HttpStatusCode.OK);
         }
 
         public Task<HttpResponseMessage> InternalServerError()
         {
-            var httpResponseMessage = new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent(string.Empty) };
-            return Task.Factory.StartNew(() => httpResponseMessage);
+            return CreateHttpResponse(HttpStatusCode.InternalServerError);
         }
 
         public Task<HttpResponseMessage> AuthenticationError()
         {
-            var httpResponseMessage = new HttpResponseMessage(HttpStatusCode.Unauthorized) { Content = new StringContent(string.Empty) };
+            return CreateHttpResponse(HttpStatusCode.Unauthorized);
+        }
+        public Task<HttpResponseMessage> HttpVersionNotSupported()
+        {
+            return CreateHttpResponse((HttpStatusCode)505);
+        }
+
+        public Task<HttpResponseMessage> CreateHttpResponse(HttpStatusCode statusCode)
+        {
+            var httpResponseMessage = new HttpResponseMessage(statusCode) { Content = new StringContent(string.Empty) };
             return Task.Factory.StartNew(() => httpResponseMessage);
         }