using System.Collections.Generic;

using System.Linq;

​

public class Bug { }

public class Drink { }

public class Test { 

  public List<Bug> Run() { return new List<Bug>(); }

}

public class Food { }

​

class Program

{

    static void Main()

    {

        QA qa=new QA();

        qa.TestAllTheThings();

    }

}

public partial class QA

{

    public List<Bug> TestAllTheThings (Food preferredSnack, Drink preferredDrink, List<Test> testList)

    {

        Eat(preferredSnack);

        Drink(preferredDrink);

        /////////////

        List<Bug> allBugs = new List<Bug>();

        for(int i=0 ; i < testList.Count ; i++)

        {            

            List<Bug> testResult = testList[i].Run();        

            allBugs.AddRange(testResult);

        }        

        /////////////

        List<Bug> allBugs = new List<Bug>();

        foreach(Test test in testList) {

            List<Bug> defects = test.Run();

            allBugs.AddRange(defects);

        }

        /////////////

        List<Bug> allBugs = testList.SelectMany( t => t.Run() ).ToList();

        ////////////

        return allBugs;    

    }

    public void Eat(Food f) {}

    public void Drink(Drink f) {}

}