CSHARP-1913: Verify that this fixes CSHARP-4251 also.

Author: rstam

tests/MongoDB.Driver.Tests/Linq/Linq3Implementation/Jira/CSharp4251Tests.cs

@@ -0,0 +1,77 @@
+/* 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.Collections.Generic;
+using System.Linq;
+using MongoDB.Driver.TestHelpers;
+using FluentAssertions;
+using Xunit;
+
+namespace MongoDB.Driver.Tests.Linq.Linq3Implementation.Jira;
+
+public class CSharp4251Tests : LinqIntegrationTest<CSharp4251Tests.ClassFixture>
+{
+    public CSharp4251Tests(ClassFixture fixture)
+        : base(fixture)
+    {
+    }
+
+    [Fact]
+    public void Test1()
+    {
+        var collection = Fixture.Collection;
+
+        var queryable = collection.AsQueryable()
+            .Select(n =>
+                new MappedObject { Items = n.Items.Select(k => new KeyValuedObject() { Count = k.Value.Count, Description = k.Value.Description, Name = k.Key }).ToList() }
+            );
+
+        var stages = Translate(collection, queryable);
+        AssertStages(stages, "{ $project : { Items : { $map : { input : { $objectToArray : '$Items' }, as : 'k', in : { Count : '$$k.v.Count', Description : '$$k.v.Description', Name : '$$k.k'  } } }, _id : 0 } }");
+    }
+
+    public class DatabaseObject
+    {
+        public int Id { get; set; }
+        public Dictionary<string, DatabaseValueObject> Items { get; set; } = new Dictionary<string, DatabaseValueObject>();
+
+    }
+
+    public class DatabaseValueObject
+    {
+        public string Description { get; set; } = string.Empty;
+        public int Count { get; set; }
+    }
+
+    public class MappedObject
+    {
+        public List<KeyValuedObject> Items { get; set; } = new List<KeyValuedObject>();
+    }
+
+    public class KeyValuedObject
+    {
+        public string Name { get; set; } = string.Empty;
+        public int Count { get; set; }
+        public string Description { get; set; } = string.Empty;
+    }
+
+    public sealed class ClassFixture : MongoCollectionFixture<DatabaseObject>
+    {
+        protected override IEnumerable<DatabaseObject> InitialData => null;
+        // [
+        //     new DatabaseObject { }
+        // ];
+    }
+}