CSHARP-4255: Fix bug and some tests.

src/MongoDB.Driver/Encryption/MongoEncryptionCreateCollectionException.cs

@@ -46,11 +46,24 @@ public MongoEncryptionCreateCollectionException(Exception innerException, BsonDo
         protected MongoEncryptionCreateCollectionException(SerializationInfo info, StreamingContext context)
             : base(info, context)
         {
+            _encryptedFields = (BsonDocument)info.GetValue("_encryptedFields", typeof(BsonDocument));
         }
 
         /// <summary>
         /// The encrypted fields.
         /// </summary>
         public BsonDocument EncryptedFields => _encryptedFields;
+
+        // public methods
+        /// <summary>
+        /// Gets the object data.
+        /// </summary>
+        /// <param name="info">The information.</param>
+        /// <param name="context">The context.</param>
+        public override void GetObjectData(SerializationInfo info, StreamingContext context)
+        {
+            base.GetObjectData(info, context);
+            info.AddValue("_encryptedFields", _encryptedFields);
+        }
     }
 }

tests/MongoDB.Driver.Tests/Encryption/MongoEncryptionCreateCollectionExceptionTests.cs

@@ -0,0 +1,47 @@
+/* Copyright 2010-present MongoDB Inc.
+*
+* 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.
+*/
+
+using System;
+using System.IO;
+using System.Runtime.Serialization.Formatters.Binary;
+using FluentAssertions;
+using MongoDB.Bson;
+using MongoDB.Driver.Encryption;
+using Xunit;
+
+namespace MongoDB.Driver.Tests.Encryption
+{
+    public class MongoEncryptionCreateCollectionExceptionTests
+    {
+        [Fact]
+        public void Serialization_should_work()
+        {
+            var subject = new MongoEncryptionCreateCollectionException(new Exception("inner"), new BsonDocument("value", 1));
+
+            var formatter = new BinaryFormatter();
+            using (var stream = new MemoryStream())
+            {
+#pragma warning disable SYSLIB0011 // BinaryFormatter serialization is obsolete
+                formatter.Serialize(stream, subject);
+                stream.Position = 0;
+                var rehydrated = (MongoEncryptionCreateCollectionException)formatter.Deserialize(stream);
+#pragma warning restore SYSLIB0011 // BinaryFormatter serialization is obsolete
+
+                rehydrated.InnerException.Message.Should().Be(subject.InnerException.Message);
+                rehydrated.EncryptedFields.Should().Be(subject.EncryptedFields).And.Should().NotBeNull();
+            }
+        }
+    }
+}