public void TestAddToSubsetSingle()
{
var model = new MutableModel();
var factory = new PropertiesTestFactory(model);
var base1 = factory.BaseClass();
var base2 = factory.BaseClass();
var base3 = factory.BaseClass();
var base4 = factory.BaseClass();
var derived1 = factory.DerivedClass();
var derived2 = factory.DerivedClass();
var derived3 = factory.DerivedClass();
var derived4 = factory.DerivedClass();
var subs = factory.UnionSingle();
subs.Subset4 = base1;
Assert.Equal(base1, subs.Union1);
Assert.Single(subs.Subset1);
Assert.Contains(base1, subs.Subset1);
Assert.Equal(base1, subs.Subset4);
Assert.Throws <ModelException>(() => subs.Subset1.Add(base2));
Assert.Equal(base1, subs.Union1);
Assert.Single(subs.Subset1);
Assert.Contains(base1, subs.Subset1);
Assert.Equal(base1, subs.Subset4);
subs.Subset5 = derived1;
Assert.Equal(derived1, subs.Union1);
Assert.Single(subs.Subset1);
Assert.Contains(derived1, subs.Subset1);
Assert.Equal(derived1, subs.Subset4);
Assert.Equal(derived1, subs.Subset5);
Assert.Throws <ModelException>(() => subs.Subset1.Add(base2));
subs.Subset5 = derived1;
Assert.Equal(derived1, subs.Union1);
Assert.Single(subs.Subset1);
Assert.Contains(derived1, subs.Subset1);
Assert.Equal(derived1, subs.Subset4);
Assert.Equal(derived1, subs.Subset5);
}