Add a test showing stack-trace preservation

Related to #1399

Author: vbfox

src/Tests/Nest.Tests.Integration/Exceptions/ElasticsearchExceptionTests.cs

@@ -47,6 +47,19 @@ public void ConnectionException_WithThrowingClient_Async()
 				.SetTimeout(500)
 				.ThrowOnElasticsearchServerExceptions());
 			Assert.Throws<WebException>(async () => await client.RootNodeInfoAsync());
+		}
+
+		[Test]
+		public void ConnectionException_WithThrowingClient_Async_PreserveStacktrace()
+		{
+			var uri = ElasticsearchConfiguration.CreateBaseUri(9494);
+			var client = new ElasticClient(new ConnectionSettings(uri)
+				.SetTimeout(500)
+				.ThrowOnElasticsearchServerExceptions());
+			var exception = Assert.Throws<WebException>(async () => await client.RootNodeInfoAsync());
+
+			var elasticClientType = typeof (ElasticClient);
+			Assert.That(exception.StackTrace, Is.Not.StringStarting(string.Format("   at {0}.{1}", elasticClientType.Namespace, elasticClientType.Name)));
 		}
 
 		[Test]