public void covariant_Contains_accepts_any_types()
{
TestCollection <Animal> c = new TestCollection <Animal>();
Animal oneElement = new Animal(null);
c.Content.Add(oneElement);
bool containsCalled = false;
c.ContainsCalled += (o, e) => { containsCalled = true; };
Assert.That(c.Contains(oneElement));
Assert.That(containsCalled, "It is our Contains method that is called."); containsCalled = false;
Assert.That(!c.Contains(56), "Contains should accept ANY object without any error.");
Assert.That(containsCalled, "It is our Contains method that is called."); containsCalled = false;
Assert.That(!c.Contains(null), "Contains should accept ANY object without any error.");
Assert.That(containsCalled); containsCalled = false;
}
public void linq_with_mere_IReadOnlyCollection_implementation_is_not_optimal_for_Count()
{
TestCollection <int> c = new TestCollection <int>();
c.Content.Add(2);
bool containsCalled = false, countCalled = false;
c.ContainsCalled += (o, e) => { containsCalled = true; };
c.CountCalled += (o, e) => { countCalled = true; };
Assert.That(c.Count == 1);
Assert.That(countCalled, "Count property on the concrete type logs the calls."); countCalled = false;
Assert.That(c.Count() == 1, "Use Linq extension methods (on the concrete type).");
Assert.That(!countCalled, "The Linq extension method did NOT call our Count.");
IEnumerable <int> cLinq = c;
Assert.That(cLinq.Count() == 1, "Linq can not use our implementation...");
Assert.That(!countCalled, "...it did not call our Count property.");
// Addressing the concrete type: it is our method that is called.
Assert.That(c.Contains(2));
Assert.That(containsCalled, "It is our Contains method that is called (not the Linq one)."); containsCalled = false;
Assert.That(!c.Contains(56));
Assert.That(containsCalled, "It is our Contains method that is called."); containsCalled = false;
Assert.That(!c.Contains(null), "Contains should accept ANY object without any error.");
Assert.That(containsCalled, "It is our Contains method that is called."); containsCalled = false;
// Unfortunately, addressing the IEnumerable base type, Linq has no way to use our methods...
Assert.That(cLinq.Contains(2));
Assert.That(!containsCalled, "Linq use the enumerator to do the job.");
Assert.That(!cLinq.Contains(56));
Assert.That(!containsCalled);
// Linq Contains() accept only parameter of the generic type.
//Assert.That( !cLinq.Contains( null ), "Contains should accept ANY object without any error." );
}
