How to use [setUp] method to arrang for a unit test. How about parameters?

public class CoffeeStrengthEstimator
{
    /// <summary>
    ///     Estimates the strength of the coffee (how many beans to use) depending on the button pressed
    /// </summary>
    /// <param name="buttonPressed"> The numeral position of the button pressed</param>
    /// <returns>An enum value indicating the estimated coffee strength</returns>
    public CoffeeStrength EstimateCoffeeStrength(int buttonPressed)
    {
        if (buttonPressed == 1)
        {
            return CoffeeStrength.Light;
        }
        else if (buttonPressed == 2)
        {
            return CoffeeStrength.Medium;
        }
        else if (buttonPressed == 3)
        {
            return CoffeeStrength.Strong;
        }
        else
        {
            throw new ArgumentException("Ogiltig knappinmatning, var god försök igen");
        }
    }
}

public enum CoffeeStrength
{
    Light,
    Medium,
    Strong
}