CSHARP-3894: Add Linq3Client property and Linq3TestHelpers class.

Author: rstam

tests/MongoDB.Driver.TestHelpers/DriverTestConfiguration.cs

@@ -19,6 +19,7 @@
 using MongoDB.Driver.Core;
 using MongoDB.Driver.Core.Clusters;
 using MongoDB.Driver.Core.Configuration;
+using MongoDB.Driver.Linq;
 using MongoDB.Driver.TestHelpers;
 
 namespace MongoDB.Driver.Tests
@@ -34,6 +35,7 @@ public static class DriverTestConfiguration
         private static CollectionNamespace __collectionNamespace;
         private static DatabaseNamespace __databaseNamespace;
         private static Lazy<IReadOnlyList<IMongoClient>> __directClientsToShardRouters;
+        private static Lazy<MongoClient> __linq3Client;
 
         // static constructor
         static DriverTestConfiguration()
@@ -45,6 +47,7 @@ static DriverTestConfiguration()
                 () => CreateDirectClientsToHostsInConnectionString(CoreTestConfiguration.ConnectionStringWithMultipleShardRouters).ToList().AsReadOnly(),
                 isThreadSafe: true);
             __collectionNamespace = new CollectionNamespace(__databaseNamespace, "testcollection");
+            __linq3Client = new Lazy<MongoClient>(CreateLinq3Client, isThreadSafe: true);
         }
 
         // public static properties
@@ -94,6 +97,14 @@ public static DatabaseNamespace DatabaseNamespace
             get { return __databaseNamespace; }
         }
 
+        /// <summary>
+        /// Gets the LINQ3 test client.
+        /// </summary>
+        public static MongoClient Linq3Client
+        {
+            get { return __linq3Client.Value; }
+        }
+
         // public static methods
         public static IEnumerable<IMongoClient> CreateDirectClientsToServersInClientSettings(MongoClientSettings settings)
         {
@@ -165,6 +176,13 @@ public static DisposableMongoClient CreateDisposableClient(MongoClientSettings s
             return new DisposableMongoClient(new MongoClient(settings));
         }
 
+        private static MongoClient CreateLinq3Client()
+        {
+            var linq3ClientSettings = Client.Settings.Clone();
+            linq3ClientSettings.LinqProvider = LinqProvider.V3;
+            return new MongoClient(linq3ClientSettings);
+        }
+
         public static MongoClientSettings GetClientSettings()
         {
             var connectionString = CoreTestConfiguration.ConnectionString.ToString();

tests/MongoDB.Driver.Tests/Linq/Linq3ImplementationTests/Linq3TestHelpers.cs

@@ -0,0 +1,45 @@
+/* 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.Linq;
+using FluentAssertions;
+using MongoDB.Bson;
+using MongoDB.Driver.Linq.Linq3Implementation;
+using MongoDB.Driver.Linq.Linq3Implementation.Translators.ExpressionToExecutableQueryTranslators;
+
+namespace MongoDB.Driver.Tests.Linq.Linq3ImplementationTests
+{
+    public static class Linq3TestHelpers
+    {
+        public static void AssertStages(BsonDocument[] stages, string[] expectedStages)
+        {
+            stages.Should().Equal(expectedStages.Select(json => BsonDocument.Parse(json)));
+        }
+
+        // in this overload the collection argument is used only to infer the TDocument type
+        public static BsonDocument[] Translate<TDocument, TResult>(IMongoCollection<TDocument> collection, IQueryable<TResult> queryable)
+        {
+            return Translate<TDocument, TResult>(queryable);
+        }
+
+        public static BsonDocument[] Translate<TDocument, TResult>(IQueryable<TResult> queryable)
+        {
+            var provider = (MongoQueryProvider<TDocument>)queryable.Provider;
+            var executableQuery = ExpressionToExecutableQueryTranslator.Translate<TDocument, TResult>(provider, queryable.Expression);
+            var stages = executableQuery.Pipeline.Stages;
+            return stages.Select(s => s.Render().AsBsonDocument).ToArray();
+        }
+    }
+}