public void Ln()
{
Aggregate(_pipeline.Json <BasicDocument, BsonDocument>("{ $project: { _id:0, Result: { $ln: \"$Value\" } } }"))
.Should().Contain(x => x["Result"].AsDouble == Math.Log(10, Math.E));
}
protected List <BsonDocument> Aggregate(string json)
{
var pl = new EmptyPipelineDefinition <TDocument>();
return(Aggregate(pl.Json <TDocument, BsonDocument>(json)));
}