CalculatorTests.xUnit.cs

using Xunit;

public class CalculatorTests
{
    private readonly Calculator _calculator;

    // Constructor-based setup (no [TestInitialize])
    public CalculatorTests()
    {
        _calculator = new Calculator();
    }

    [Fact] // Equivalent to [TestMethod] in MSTest
    public void Add_ShouldReturnCorrectSum_WhenNumbersAreIntegers()
    {
        var result = _calculator.Add(2, 3);
        Assert.Equal(5, result); // xUnit assertion
    }

    [Theory] // Supports data-driven tests
    [InlineData(2, 3, 5)]
    [InlineData(-1, -1, -2)]
    public void Add_ShouldReturnExpectedResults_WhenNumbersAreIntegers(int a, int b, int expected)
    {
        var result = _calculator.Add(a, b);
        Assert.Equal(expected, result);
    }
}