public void Mul_MultiplyingWhereStackCountIsLessThanTwo_ThrowsException()
 {
     var calc = new StackCalculator();
     calc.Push(200);
     Exception e = Assert.Throws<ArgumentException>(() => calc.Mul());
 }
 public void Mul_MultiplyingValues_ValuesMultiplied()
 {
     var calc = new StackCalculator();
     calc.Push(100);
     calc.Push(200);
     calc.Mul();
     Expect(calc.Pop(), Is.EqualTo(200*100));
 }