CSHARP-3915: Skip Densify tests on servers that don't support it.

Author: rstam

src/MongoDB.Driver.Core/Core/Misc/Feature.cs

@@ -57,6 +57,7 @@ public class Feature
         private static readonly Feature __createIndexesCommand = new Feature("CreateIndexesCommand", WireVersion.Server26);
         private static readonly Feature __createIndexesUsingInsertOperations = new Feature("CreateIndexesUsingInsertOperations", WireVersion.Zero, WireVersion.Server42);
         private static readonly Feature __currentOpCommand = new Feature("CurrentOpCommand", WireVersion.Server32);
+        private static readonly Feature __densifyStage = new Feature("DensifyStage", WireVersion.Server51);
         private static readonly Feature __documentValidation = new Feature("DocumentValidation", WireVersion.Server32);
         private static readonly Feature __directConnectionSetting = new Feature("DirectConnectionSetting", WireVersion.Server44);
         private static readonly Feature __eval = new Feature("Eval", WireVersion.Zero, WireVersion.Server42);
@@ -306,6 +307,11 @@ public class Feature
         [Obsolete("This property will be removed in a later release.")]
         public static Feature CurrentOpCommand => __currentOpCommand;
 
+        /// <summary>
+        /// Gets the aggregate $densify stage feature.
+        /// </summary>
+        public static Feature DensifyStage => __densifyStage;
+
         /// <summary>
         /// Gets the document validation feature.
         /// </summary>

tests/MongoDB.Driver.Tests/Jira/CSharp3915Tests.cs

@@ -17,6 +17,8 @@
 using System.Linq;
 using FluentAssertions;
 using MongoDB.Bson.IO;
+using MongoDB.Driver.Core.Misc;
+using MongoDB.Driver.Core.TestHelpers.XunitExtensions;
 using MongoDB.Driver.Linq;
 using MongoDB.Driver.Tests.Linq.Linq3ImplementationTests;
 using Xunit;
@@ -31,6 +33,7 @@ public class CSharp3915Tests : Linq3IntegrationTest
         [InlineData(true)]
         public void Densify_time_series_data_example_using_aggregate_should_work(bool usingExpressions)
         {
+            RequireServer.Check().Supports(Feature.DensifyStage);
             var collection = CreateWeatherCollection();
             var subject = collection.Aggregate();
 
@@ -76,6 +79,7 @@ public void Densify_time_series_data_example_using_aggregate_should_work(bool us
         [Fact]
         public void Densify_time_series_data_example_using_linq_should_work()
         {
+            RequireServer.Check().Supports(Feature.DensifyStage);
             var collection = CreateWeatherCollection();
             var subject = collection.AsQueryable();
 
@@ -113,6 +117,7 @@ public void Densify_time_series_data_example_using_linq_should_work()
         [InlineData(true)]
         public void Densify_the_full_range_of_values_example_using_aggregate_should_work(bool usingExpressions)
         {
+            RequireServer.Check().Supports(Feature.DensifyStage);
             var collection = CreateCoffeeCollection();
             var subject = collection.Aggregate();
 
@@ -162,6 +167,7 @@ public void Densify_the_full_range_of_values_example_using_aggregate_should_work
         [Fact]
         public void Densify_the_full_range_of_values_example_using_linq_should_work()
         {
+            RequireServer.Check().Supports(Feature.DensifyStage);
             var collection = CreateCoffeeCollection();
             var subject = collection.AsQueryable();
 
@@ -202,6 +208,7 @@ public void Densify_the_full_range_of_values_example_using_linq_should_work()
         [InlineData(true)]
         public void Densify_values_within_each_partition_example_using_aggregate_should_work(bool usingExpressions)
         {
+            RequireServer.Check().Supports(Feature.DensifyStage);
             var collection = CreateCoffeeCollection();
             var subject = collection.Aggregate();
 
@@ -243,6 +250,7 @@ public void Densify_values_within_each_partition_example_using_aggregate_should_
         [Fact]
         public void Densify_values_within_each_partition_example_using_linq_should_work()
         {
+            RequireServer.Check().Supports(Feature.DensifyStage);
             var collection = CreateCoffeeCollection();
             var subject = collection.AsQueryable();