public class StringCalculatorShould
{
    [Fact]
    public void DefaultToZeroOnEmptyString()
    {
        var stringCalculator = new StringCalculator();

        var result = stringCalculator.Calculate("");

        result.ShouldBe(0);
    }

    [Theory]
    [InlineData("1", 1)]
    [InlineData("155", 155)]
    [InlineData("9", 9)]
    public void ReturnNumberIfOneArgument(string input, int expected)
    {
        var stringCalculator = new StringCalculator();

        var result = stringCalculator.Calculate(input);

        result.ShouldBe(expected);
    }

    [Theory]
    [InlineData("1,1", 2)]
    [InlineData("10,1", 11)]
    [InlineData("99,11", 110)]
    public void SumNumbersSeparatedByComma(string input, int expected)
    {
        var stringCalculator = new StringCalculator();

        var result = stringCalculator.Calculate(input);

        result.ShouldBe(expected);
    }
}