public void Unite()
{
var intervalA = new DateTimeInterval(new DateTime(2000, 12, 1, 5, 0, 0), new DateTime(2001, 1, 2, 12, 0, 0));
var intervalB = new DateTimeInterval(new DateTime(2001, 1, 2, 12, 0, 0), new DateTime(2001, 2, 2, 12, 6, 0));
var unitedInterval = intervalB.Unite(intervalA);
Assert.AreEqual(unitedInterval, new DateTimeInterval(new DateTime(2000, 12, 1, 5, 0, 0), new DateTime(2001, 2, 2, 12, 6, 0)));
intervalB = new DateTimeInterval(new DateTime(2001, 1, 2, 13, 0, 0), new DateTime(2001, 2, 2, 12, 6, 0));
unitedInterval = intervalA.Unite(intervalB);
Assert.AreEqual(unitedInterval, null);
intervalB = new DateTimeInterval(new DateTime(2001, 1, 1, 0, 0, 0), new DateTime(2001, 2, 2, 12, 6, 0));
unitedInterval = intervalA.Unite(intervalB);
Assert.AreEqual(unitedInterval, new DateTimeInterval(new DateTime(2000, 12, 1, 5, 0, 0), new DateTime(2001, 2, 2, 12, 6, 0)));
intervalB = new DateTimeInterval(intervalA.StartDate, intervalA.FinishDate);
unitedInterval = intervalA.Unite(intervalB);
Assert.AreEqual(unitedInterval, intervalA);
intervalB = new DateTimeInterval(new DateTime(1900, 1, 1, 0, 0, 0), new DateTime(2010, 2, 2, 12, 6, 0));
unitedInterval = intervalA.Unite(intervalB);
Assert.AreEqual(unitedInterval, intervalB);
var date = new DateTime(2000, 1, 1, 0, 0, 0);
intervalA = intervalB = new DateTimeInterval(date, date);
unitedInterval = intervalA.Unite(intervalB);
Assert.AreEqual(unitedInterval, intervalA);
}
