public void TestAsNullableDateTime()
{
var utcNow = DateTime.UtcNow;
var utcNowTruncated = utcNow.AddTicks(-(utcNow.Ticks % 10000));
BsonValue v = utcNow;
BsonValue n = BsonNull.Value;
BsonValue s = "";
Assert.AreEqual(utcNowTruncated, v.ToNullableUniversalTime());
Assert.AreEqual(null, n.ToNullableUniversalTime());
#pragma warning disable 618
Assert.Throws <InvalidCastException>(() => { var x = s.AsNullableDateTime; });
#pragma warning restore
Assert.Throws <NotSupportedException>(() => { var x = s.ToNullableUniversalTime(); });
}