C# - guide with Inheritance and Overriding Methods in .NET 6 Leading to advanced patterns
I'm writing unit tests and I've searched everywhere and can't find a clear answer... I'm working with a question with method overriding in my C# application that uses .NET 6. I have a base class `Animal` with a virtual method `Speak()` and a derived class `Dog` that overrides this method. However, when I call `Speak()` on an instance of `Dog`, it sometimes behaves as if it’s calling the base method instead of the overridden one. Here's the code: ```csharp public class Animal { public virtual string Speak() => "Some sound"; } public class Dog : Animal { public override string Speak() => "Woof"; } public class Program { public static void Main(string[] args) { Animal myDog = new Dog(); Console.WriteLine(myDog.Speak()); // Expected: "Woof" CallSpeak(myDog); } public static void CallSpeak(Animal animal) { Console.WriteLine(animal.Speak()); } } ``` The output is as expected when I run the `Main` method directly, showing "Woof". However, I’m struggling with a more complex scenario where I pass `Animal` objects around, and sometimes the overridden method does not get called. I've debugged this and ensured that the instances are indeed of type `Dog`, yet the output is inconsistent. The scenario seems to arise when I deal with collections of animals, for instance: ```csharp List<Animal> animals = new List<Animal>() { new Dog(), new Animal() }; foreach (var animal in animals) { Console.WriteLine(animal.Speak()); } ``` Here, I get "Woof" for the `Dog` instance, but if I later modify the `List<Animal>` to hold a reference to an `Animal` type that isn't overridden properly, it results in unexpected behavior, such as erroneously calling the method in the base class. Is there something I’m missing regarding polymorphism in collections? I'd appreciate any insights or best practices on how to ensure the correct method is called, especially in scenarios involving lists and inheritance. Thank you! My development environment is Linux. I'd really appreciate any guidance on this.