CSHARP-2093: updated incompatible server exception message.

Author: craiggwilson

src/MongoDB.Driver.Core/Core/Clusters/Cluster.cs

@@ -39,9 +39,18 @@ internal abstract class Cluster : ICluster
         // static fields
         private static readonly TimeSpan __minHeartbeatInterval = TimeSpan.FromMilliseconds(500);
         private static readonly Range<int> __supportedWireVersionRange = new Range<int>(2, 6);
+        private static readonly SemanticVersion __minSupportedServerVersion = new SemanticVersion(2, 6, 0);
         private static readonly IServerSelector __randomServerSelector = new RandomServerSelector();
 
         // static properties
+        /// <summary>
+        /// Gets the minimum supported server version.
+        /// </summary>
+        /// <value>
+        /// The minimum supported server version
+        /// </value>
+        public static SemanticVersion MinSupportedServerVersion => __minSupportedServerVersion;
+
         /// <summary>
         /// Gets the supported wire version range.
         /// </summary>
@@ -416,7 +425,7 @@ public IServer SelectServer()
                     }
                 }
 
-                ThrowIfIncompatible(_description);
+                MongoIncompatibleDriverException.ThrowIfNotSupported(_description);
 
                 var connectedServers = _description.Servers.Where(s => s.State == ServerState.Connected);
                 var selectedServers = _selector.SelectServers(_description, connectedServers).ToList();
@@ -488,16 +497,6 @@ private IServerSelector DecorateSelector(IServerSelector selector)
 
                 return selector;
             }
-            private void ThrowIfIncompatible(ClusterDescription description)
-            {
-                var isIncompatible = description.Servers
-                    .Any(sd => sd.WireVersionRange != null && !sd.WireVersionRange.Overlaps(__supportedWireVersionRange));
-
-                if (isIncompatible)
-                {
-                    throw new MongoIncompatibleDriverException(description);
-                }
-            }
         }
 
         private sealed class WaitForDescriptionChangedHelper : IDisposable

src/MongoDB.Driver.Core/MongoIncompatibleDriverException.cs

@@ -1,4 +1,4 @@
-/* Copyright 2013-2016 MongoDB Inc.
+/* Copyright 2013-2017 MongoDB Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -14,10 +14,12 @@
 */
 
 using System;
+using System.Linq;
 #if NET45
 using System.Runtime.Serialization;
 #endif
 using MongoDB.Driver.Core.Clusters;
+using MongoDB.Driver.Core.Misc;
 
 namespace MongoDB.Driver
 {
@@ -31,11 +33,30 @@ public class MongoIncompatibleDriverException : MongoClientException
     {
         #region static
         // static methods
-        private static string FormatMessage(ClusterDescription clusterDescription)
+        internal static void ThrowIfNotSupported(ClusterDescription description)
         {
-            return string.Format(
-                "This version of the driver is not compatible with one or more of the servers to which it is connected: {0}.",
-                clusterDescription);
+            var isIncompatible = description.Servers
+                .Any(sd => sd.WireVersionRange != null && !sd.WireVersionRange.Overlaps(Cluster.SupportedWireVersionRange));
+
+            if (isIncompatible)
+            {
+                throw new MongoIncompatibleDriverException(description);
+            }
+        }
+
+        private static string FormatMessage(ClusterDescription description)
+        {
+            var incompatibleServer = description.Servers
+                .FirstOrDefault(sd => sd.WireVersionRange != null && !sd.WireVersionRange.Overlaps(Cluster.SupportedWireVersionRange));
+
+            if (incompatibleServer.WireVersionRange.Max < Cluster.SupportedWireVersionRange.Min)
+            {
+                return $"Server at {EndPointHelper.ToString(incompatibleServer.EndPoint)} reports wire version {incompatibleServer.WireVersionRange.Max},"
+                    + $" but this version of the driver requires at least {Cluster.SupportedWireVersionRange.Min} (MongoDB {Cluster.MinSupportedServerVersion}).";
+            }
+
+            return $"Server at {EndPointHelper.ToString(incompatibleServer.EndPoint)} requires wire version {incompatibleServer.WireVersionRange.Min},"
+                + $" but this version of the driver only supports up to {Cluster.SupportedWireVersionRange.Max}.";
         }
         #endregion
 

tests/MongoDB.Driver.Core.Tests/Core/Clusters/ClusterTests.cs

@@ -304,15 +304,16 @@ public void SelectServer_should_throw_if_the_matched_server_cannot_be_found_and_
         }
 
         [Theory]
-        [ParameterAttributeData]
-        public void SelectServer_should_throw_if_any_servers_are_incompatible(
-            [Values(false, true)]
-            bool async)
+        [InlineData(0, 0, false)]
+        [InlineData(0, 0, true)]
+        [InlineData(10, 12, false)]
+        [InlineData(10, 12, true)]
+        public void SelectServer_should_throw_if_any_servers_are_incompatible(int min, int max, bool async)
         {
             var subject = CreateSubject();
             subject.Initialize();
 
-            var connected = ServerDescriptionHelper.Connected(subject.Description.ClusterId, wireVersionRange: new Range<int>(10, 12));
+            var connected = ServerDescriptionHelper.Connected(subject.Description.ClusterId, wireVersionRange: new Range<int>(min, max));
             subject.SetServerDescriptions(connected);
             _capturedEvents.Clear();
 
@@ -328,7 +329,7 @@ public void SelectServer_should_throw_if_any_servers_are_incompatible(
                 act = () => subject.SelectServer(selector, CancellationToken.None);
             }
 
-            act.ShouldThrow<MongoException>();
+            act.ShouldThrow<MongoIncompatibleDriverException>();
 
             _capturedEvents.Next().Should().BeOfType<ClusterSelectingServerEvent>();
             _capturedEvents.Next().Should().BeOfType<ClusterSelectingServerFailedEvent>();