public void TestIsSequential()
{
var a = new History ();
a.Add (new DateTime (2003, 1, 1));
a.Add (new DateTime (2002, 12, 18));
Assert.False (a.IsSequential ());
var b = new History ();
b.Add (new DateTime (2002, 12, 18));
b.Add (new DateTime (2003, 1, 1));
Assert.True (b.IsSequential ());
}