Answers for "what is a unit testable code"

what is a unit testable code

public class SomeClass
{
    public SomeClass(calculatedParams)
    {
        ...
    }
}

    public interface ISomeClassCreator
    {
        SomeClass Create(params);
    }

public class SomeClassCreator: ISomeClassCreator
{
    public SomeClass Create(params)
    {
        ...
    }
}