public async Task GivenAnIntegerWhenFizBuzThenProduceString(int input, string expected)
        {
            var calculator = new RateCalculator();

            var output = await calculator.FizBuz(input);

            output.Should().Be(expected);
        }
        public async Task GivenThreeWhenFizBuzThenFiz()
        {
            //AAA

            //Arrange
            var       calculator = new RateCalculator();
            const int input      = 3;

            //Act
            var output = await calculator.FizBuz(input);

            //Assert
            output.Should().Be("Fiz");
        }