public void EmptyTrait_is_everywhere()
{
CKTrait m = Context.EmptyTrait;
Assert.That(m.ToString() == String.Empty, "Empty trait is the empty string.");
Assert.That(m.IsAtomic, "Empty trait is considered as atomic.");
Assert.That(m.AtomicTraits.Count == 0, "Empty trait has no atomic traits inside.");
Assert.That(Context.FindOrCreate((string)null) == m, "Null gives the empty trait.");
Assert.That(Context.FindOrCreate("") == m, "Obtaining empty string gives the empty trait.");
Assert.That(Context.FindOrCreate("+") == m, "Obtaining '+' gives the empty trait.");
Assert.Throws <ArgumentException>(() => Context.FindOrCreate(" \t \n "), "No \n inside.");
Assert.Throws <ArgumentException>(() => Context.FindOrCreate(" \r "), "No \r inside.");
Assert.That(Context.FindOrCreate("+ \t +") == m, "Leading and trailing '+' are ignored.");
Assert.That(Context.FindOrCreate("++++") == m, "Multiple + are ignored");
Assert.That(Context.FindOrCreate("++ +++ + \t +") == m, "Multiple empty strings leads to empty trait.");
Assert.That(Context.FindOnlyExisting(null), Is.Null);
Assert.That(Context.FindOnlyExisting(""), Is.Null);
Assert.That(Context.FindOnlyExisting(" "), Is.Null);
Assert.That(Context.FindOnlyExisting(" ++ + "), Is.Null);
Assert.That(Context.FindOnlyExisting("NONE"), Is.Null);
Assert.That(Context.FindOnlyExisting("NO+NE"), Is.Null);
Assert.That(Context.FindOnlyExisting("N+O+N+E"), Is.Null);
}
