Drill 21: Find the core line — Testing with xUnit

using Xunit;

public class Calculator
{
    public int Add(int a, int b) => a + b;

    public int Divide(int a, int b)
    {
        if (b == 0) throw new ArgumentException("Cannot divide by zero");
        return a / b;
    }
}

public class CalculatorTests
{
    private readonly Calculator calculator = new Calculator();

    [Fact]
    public void Add_ReturnsSum()
    {
        var result = calculator.Add(2, 3);
        Assert.Equal(5, result);
    }

    [Theory]
    [InlineData(6, 3, 2)]
    [InlineData(9, 3, 3)]
    public void Divide_ReturnsQuotient(int a, int b, int expected)
    {
        Assert.Equal(expected, calculator.Divide(a, b));
    }

    [Fact]
    public void Divide_ByZero_Throws()
    {
        Assert.Throws<ArgumentException>(() => calculator.Divide(1, 0));
    }
}