public void AddScoreAtLeast0()
{
var model = new SpellingModel();
model.score = 30;
model.AddScore(-1);
Assert.AreEqual(29, model.score);
model.AddScore(-20);
Assert.AreEqual(9, model.score);
model.AddScore(-20);
Assert.AreEqual(0, model.score);
model.AddScore(-1);
Assert.AreEqual(0, model.score);
}