public async Task WriteRawValueAsync()
{
await ExceptionAssert.ThrowsAsync <JsonWriterException>(async() =>
{
MemoryStream ms = new MemoryStream();
BsonDataWriter writer = new BsonDataWriter(ms);
await writer.WriteStartArrayAsync();
await writer.WriteRawValueAsync("fail");
}, "Cannot write raw JSON as BSON. Path ''.");
}