feat: make RetriableServerErrorStatusCodes public (#1156)

Author: maxkoshevoi

src/SendGrid/Reliability/ReliabilitySettings.cs

@@ -4,6 +4,8 @@
 // </copyright>
 
 using System;
+using System.Collections.Generic;
+using System.Net;
 
 namespace SendGrid.Helpers.Reliability
 {
@@ -89,5 +91,21 @@ public ReliabilitySettings(int maximumNumberOfRetries, TimeSpan minimumBackoff,
         /// Gets the value that will be used to calculate a random delta in the exponential delay between retries. Defaults to 1 second.
         /// </summary>
         public TimeSpan DeltaBackOff { get; }
+
+        /// <summary>
+        /// Gets status codes for which request would be retied.
+        /// </summary>
+        public List<HttpStatusCode> RetriableServerErrorStatusCodes { get; } = new List<HttpStatusCode>(DefaultRetriableServerErrorStatusCodes);
+
+        /// <summary>
+        /// Gets default status codes for which request would be retied.
+        /// </summary>
+        public static List<HttpStatusCode> DefaultRetriableServerErrorStatusCodes { get; } = new List<HttpStatusCode>()
+        {
+            HttpStatusCode.InternalServerError,
+            HttpStatusCode.BadGateway,
+            HttpStatusCode.ServiceUnavailable,
+            HttpStatusCode.GatewayTimeout,
+        };
     }
 }

src/SendGrid/Reliability/RetryDelegatingHandler.cs

@@ -4,8 +4,7 @@
 // </copyright>
 
 using System;
-using System.Collections.Generic;
-using System.Net;
+using System.Linq;
 using System.Net.Http;
 using System.Threading;
 using System.Threading.Tasks;
@@ -17,15 +16,6 @@ namespace SendGrid.Helpers.Reliability
     /// </summary>
     public class RetryDelegatingHandler : DelegatingHandler
     {
-        private static readonly List<HttpStatusCode> RetriableServerErrorStatusCodes =
-            new List<HttpStatusCode>()
-            {
-                HttpStatusCode.InternalServerError,
-                HttpStatusCode.BadGateway,
-                HttpStatusCode.ServiceUnavailable,
-                HttpStatusCode.GatewayTimeout,
-            };
-
         private readonly ReliabilitySettings settings;
 
         /// <summary>
@@ -69,7 +59,7 @@ protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage
                 {
                     responseMessage = await base.SendAsync(request, cancellationToken).ConfigureAwait(false);
 
-                    ThrowHttpRequestExceptionIfResponseCodeCanBeRetried(responseMessage);
+                    this.ThrowHttpRequestExceptionIfResponseCodeCanBeRetried(responseMessage);
 
                     sent = true;
                 }
@@ -101,9 +91,9 @@ protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage
             return responseMessage;
         }
 
-        private static void ThrowHttpRequestExceptionIfResponseCodeCanBeRetried(HttpResponseMessage responseMessage)
+        private void ThrowHttpRequestExceptionIfResponseCodeCanBeRetried(HttpResponseMessage responseMessage)
         {
-            if (RetriableServerErrorStatusCodes.Contains(responseMessage.StatusCode))
+            if (this.settings.RetriableServerErrorStatusCodes.Contains(responseMessage.StatusCode))
             {
                 throw new HttpRequestException(string.Format("Http status code '{0}' indicates server error", responseMessage.StatusCode));
             }

tests/SendGrid.Tests/Reliability/ReliabilitySettingsTests.cs

@@ -99,6 +99,7 @@ public void ShouldPassValidValuesFromDefaultConstruct()
             Assert.Equal(TimeSpan.Zero, defaultSettings.MinimumBackOff);
             Assert.Equal(TimeSpan.Zero, defaultSettings.DeltaBackOff);
             Assert.Equal(0, defaultSettings.MaximumNumberOfRetries);
+            Assert.Equal(ReliabilitySettings.DefaultRetriableServerErrorStatusCodes, defaultSettings.RetriableServerErrorStatusCodes);
         }
 
         [Fact]