public void InstancesWithDuplicateTypes()
{
var collection = new IInterface[] { new A(), new B(), new A() };
var result = collection.IsContainingInstancesOfDifferentTypes();
result.Should().BeFalse();
}
public void ItemNull()
{
var collection = new IInterface[] { new A(), null, new C() };
Action act = () => collection.IsContainingInstancesOfDifferentTypes();
act.Should().Throw <CollectionException>()
.And.Message.Should().Contain($"The collection contains null at index 1");
}