public void TestUpdate()
{
IExternalSurrogate s1 = new CGuidSurrogate();
IExternalSurrogate s2 = new CDateTimeSurrogate();
IExternalSurrogate s3 = new CUtcDateTimeSurrogate();
IExternalSurrogate accum = null;
accum = CExternalSurrogatePair.Update(accum, null);
Assert.IsNull(accum, "Updating NULL with NULL should result in NULL");
accum = CExternalSurrogatePair.Update(accum, s1);
Assert.AreSame(s1, accum, "After UPDATEing null with s1, the accumulator should be s1");
accum = CExternalSurrogatePair.Update(accum, null);
Assert.AreSame(s1, accum, "After UPDATEing the s1 accumulator with NULL, the accumulator should not have changed");
accum = CExternalSurrogatePair.Update(accum, s2);
Assert.AreEqual(typeof(CExternalSurrogatePair), accum.GetType(), "After UPDATEing accumulator with s2, the accumulator should now be a surrogate Pair.");
Assert.AreSame(s1, (accum as CExternalSurrogatePair).Surrogate1, "The first surrogate of the Pair should be s1");
Assert.AreSame(s2, (accum as CExternalSurrogatePair).Surrogate2, "The second surrogate of the Pair should be s2");
accum = CExternalSurrogatePair.Update(accum, s3);
Assert.AreEqual(typeof(CExternalSurrogatePair), accum.GetType(), "After UPDATEing accumulator with s3, the accumulator should still be a surrogate Pair.");
Assert.AreEqual(typeof(CExternalSurrogatePair), (accum as CExternalSurrogatePair).Surrogate1.GetType(), "The Type of the first surrogate of the Pair should be a Pair");
Assert.AreEqual(typeof(CUtcDateTimeSurrogate), (accum as CExternalSurrogatePair).Surrogate2.GetType(), "The Type of the second surrogate of the Pair should be the UTC Time surrogate");
}
/// <summary>
/// Construct the Pair using Two separate surrogates.
/// </summary>
/// <param name="_surrogate1">The 1st surrogate</param>
/// <param name="_surrogate2">The 2nd surrogate</param>
public CExternalSurrogatePair(IExternalSurrogate _surrogate1, IExternalSurrogate _surrogate2)
{
if (_surrogate1 == null || _surrogate2 == null)
{
throw new ArgumentNullException("Not allowed to construct a SurrogatePair with any NULL surrogates.");
}
Surrogate1 = _surrogate1;
Surrogate2 = _surrogate2;
}
/// <summary>
/// This static method acts as an "accumulator" where, as new surrogates are "found"
/// that should be called in turn for a given Type, new Pairs are called and connected
/// to each other.
/// </summary>
/// <param name="_working">
/// The "Working" variable that is being "accumulated into"
/// </param>
/// <param name="_next">
/// The "next" IExternalSurrogate that should be "accumulated into" the working
/// surrogate
/// </param>
/// <returns>
/// An IExternalSurrogate representing the "current" state of the "accumulator"
/// </returns>
public static IExternalSurrogate Update(IExternalSurrogate _working, IExternalSurrogate _next)
{
if (_working == null)
{
return(_next);
}
if (_next == null)
{
return(_working);
}
return(new CExternalSurrogatePair(_working, _next));
}
