CSHARP-2107: Verify that issue is not present in LINQ3.

Author: rstam

tests/MongoDB.Driver.Tests/Linq/Linq3ImplementationTests/Jira/CSharp2107Tests.cs

@@ -0,0 +1,110 @@
+/* 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 FluentAssertions;
+using MongoDB.Bson;
+using MongoDB.Bson.Serialization.Attributes;
+using Xunit;
+
+namespace MongoDB.Driver.Tests.Linq.Linq3ImplementationTests.Jira
+{
+    public class CSharp2107Tests : Linq3IntegrationTest
+    {
+        [Fact]
+        public void Aggregate_Project_should_work()
+        {
+            var collection = CreateCollection();
+
+            var aggregate = collection.Aggregate()
+                .Project(doc => new
+                {
+                    UserIsCustomer = doc.Users.Where(user => user.Identity.IdentityType == IdentityType.Type1)
+                });
+
+            var stages = Translate(collection, aggregate);
+            AssertStages(stages, "{ $project : { UserIsCustomer : { $filter : { input : '$Users', as : 'user', cond : { $eq : ['$$user.Identity.IdentityType', 'Type1'] } } }, _id : 0 } }");
+
+            var results = aggregate.ToList();
+            results.Should().HaveCount(1);
+            results[0].UserIsCustomer.Select(u => u.UserId).Should().Equal(1);
+        }
+
+        [Fact]
+        public void Queryable_Select_should_work()
+        {
+            var collection = CreateCollection();
+
+            var queryable = collection.AsQueryable()
+                .Select(doc => new
+                {
+                    UserIsCustomer = doc.Users.Where(user => user.Identity.IdentityType == IdentityType.Type1)
+                });
+
+            var stages = Translate(collection, queryable);
+            AssertStages(stages, "{ $project : { UserIsCustomer : { $filter : { input : '$Users', as : 'user', cond : { $eq : ['$$user.Identity.IdentityType', 'Type1'] } } }, _id : 0 } }");
+
+            var results = queryable.ToList();
+            results.Should().HaveCount(1);
+            results[0].UserIsCustomer.Select(u => u.UserId).Should().Equal(1);
+        }
+
+        private IMongoCollection<Customer> CreateCollection()
+        {
+            var collection = GetCollection<Customer>();
+
+            var documents = new[]
+            {
+                new Customer
+                {
+                    Id = 1,
+                    Users = new[]
+                    {
+                        new User { UserId = 1, Identity = new Identity { IdentityType = IdentityType.Type1 } },
+                        new User { UserId = 2, Identity = new Identity { IdentityType = IdentityType.Type2 } }
+                    }
+                }
+            };
+            CreateCollection(collection, documents);
+
+            return collection;
+        }
+
+        private class Customer
+        {
+            public int Id { get; set; }
+            public IEnumerable<User> Users { get; set; }
+        }
+
+        private class User
+        {
+            public int UserId { get; set; }
+            public Identity Identity { get; set; }
+        }
+
+        private class Identity
+        {
+            [BsonRepresentation(BsonType.String)]
+            public IdentityType IdentityType { get; set; }
+        }
+
+        private enum IdentityType
+        {
+            Type1,
+            Type2
+        }
+    }
+}