CSHARP-1777: Fix regression in filter builder with Contains in an expression.

Author: rstam

src/MongoDB.Driver/Linq/Processors/Pipeline/PipelineBindingContext.cs

@@ -1,4 +1,4 @@
-/* Copyright 2015 MongoDB Inc.
+/* Copyright 2015-2017 MongoDB Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -92,11 +92,16 @@ public IBsonSerializer GetSerializer(Type type, Expression node)
                 serializer = _serializerRegistry.GetSerializer(type);
                 if (node != null)
                 {
-                    var childConfigurable = serializer as IChildSerializerConfigurable;
-                    if (childConfigurable != null)
+                    var childConfigurableSerializer = serializer as IChildSerializerConfigurable;
+                    if (childConfigurableSerializer != null)
                     {
-                        var childSerializer = GetSerializer(node.Type, node);
-                        serializer = SerializerHelper.RecursiveConfigureChildSerializer(childConfigurable, childSerializer);
+                        var nodeSerializer = GetSerializer(node.Type, node);
+                        var deepestChildSerializer = SerializerHelper.GetDeepestChildSerializer(childConfigurableSerializer);
+
+                        if (nodeSerializer.ValueType == deepestChildSerializer.ValueType)
+                        {
+                            serializer = SerializerHelper.RecursiveConfigureChildSerializer(childConfigurableSerializer, nodeSerializer);
+                        }
                     }
                 }
             }

src/MongoDB.Driver/Linq/SerializerHelper.cs

@@ -1,4 +1,4 @@
-/* Copyright 2015-2016 MongoDB Inc.
+/* Copyright 2015-2017 MongoDB Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -72,5 +72,18 @@ public static IBsonSerializer RecursiveConfigureChildSerializer(IChildSerializer
 
             return configurable.WithChildSerializer(childSerializer);
         }
+
+        public static IBsonSerializer GetDeepestChildSerializer(IChildSerializerConfigurable childConfigurableSerializer)
+        {
+            IBsonSerializer deepestChildSerializer = null;
+
+            while (childConfigurableSerializer != null)
+            {
+                deepestChildSerializer = childConfigurableSerializer.ChildSerializer;
+                childConfigurableSerializer = deepestChildSerializer as IChildSerializerConfigurable;
+            }
+
+            return deepestChildSerializer;
+        }
     }
 }

tests/MongoDB.Driver.Tests/FilterDefinitionBuilderEnumerableNullableEnumContainsNullableEnumTests.cs

@@ -0,0 +1,52 @@
+/* Copyright 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.
+* 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.Collections.Generic;
+using System.Linq;
+using FluentAssertions;
+using MongoDB.Bson;
+using MongoDB.Bson.Serialization;
+using MongoDB.Bson.Serialization.Attributes;
+using Xunit;
+
+namespace MongoDB.Driver.Tests
+{
+    public class FilterDefinitionBuilderEnumerableNullableEnumContainsNullableEnumTests
+    {
+        private static IBsonSerializerRegistry __registry = BsonSerializer.SerializerRegistry;
+        private static IBsonSerializer<C> __serializer = BsonSerializer.SerializerRegistry.GetSerializer<C>();
+        private static FilterDefinitionBuilder<C> __subject = Builders<C>.Filter;
+
+        public enum E { A, B };
+
+        public class C
+        {
+            public int Id;
+            [BsonRepresentation(BsonType.String)]
+            public E? P;
+        }
+
+        [Fact]
+        public void Contains_should_render_correctly()
+        {
+            var values = (IEnumerable<E?>)new E?[] { null, E.A, E.B };
+            var filter = __subject.Where(x => values.Contains(x.P));
+
+            var result = filter.Render(__serializer, __registry);
+            
+            result.Should().Be("{ P : { $in : [ null, 'A', 'B' ] } }");
+        }
+    }
+}

tests/MongoDB.Driver.Tests/MongoDB.Driver.Tests.csproj

@@ -112,6 +112,7 @@
     <Compile Include="FilterDefinitionBuilderEnumComparedToEnumWithStringRepresentationTests.cs" />
     <Compile Include="FilterDefinitionBuilderEnumComparedToNullableEnumTests.cs" />
     <Compile Include="FilterDefinitionBuilderEnumComparedToNullableEnumWithStringRepresentationTests.cs" />
+    <Compile Include="FilterDefinitionBuilderEnumerableNullableEnumContainsNullableEnumTests.cs" />
     <Compile Include="FilterDefinitionBuilderIntArrayComparedToEnumerableIntTests.cs" />
     <Compile Include="FilterDefinitionBuilderEnumComparedToEnumTests.cs" />
     <Compile Include="FilterDefinitionBuilderIntComparedToIntTests.cs" />