Parameterized Tests with xUnit Example

xUnitDataTests.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using Xunit;

public class StringFormatter
{
    public string Reverse(string input)
    {
        switch (input)
        {
            case "abc":
                return "cba";
            case "hello":
                return "olleh";
            case "world":
                return "dlrow";
            default:
                throw new ArgumentException($"No reverse mapping defined for '{input}'.");
        }
    }
}

public class StringFormatterTests
{
    // Using InlineData
    [Theory]
    [InlineData("abc", "cba")]
    [InlineData("hello", "olleh")]
    [InlineData("world", "dlrow")]
    public void Reverse_WithInlineData_ReturnsCorrectResult(string input, string expected)
    {
        var stringFormatter = new StringFormatter();
        var result = stringFormatter.Reverse(input);
        Assert.Equal(expected, result);
    }

    // Using TheoryData
    public static TheoryData<string, string> ReverseTestData =>
        new TheoryData<string, string>
        {
            { "abc", "cba" },
            { "hello", "olleh" },
            { "world", "dlrow" }
        };

    [Theory]
    [MemberData(nameof(ReverseTestData))]
    public void Reverse_WithTheoryData_ReturnsCorrectResult(string input, string expected)
    {
        var stringFormatter = new StringFormatter();
        var result = stringFormatter.Reverse(input);
        Assert.Equal(expected, result);
    }

    // Using ClassData
    [Theory]
    [ClassData(typeof(ReverseTestCases))]
    public void Reverse_WithClassData_ReturnsCorrectResult(string input, string expected)
    {
        var stringFormatter = new StringFormatter();
        var result = stringFormatter.Reverse(input);
        Assert.Equal(expected, result);
    }
}

public class ReverseTestCases : IEnumerable<object[]>
{
    public IEnumerator<object[]> GetEnumerator()
    {
        yield return new object[] { "abc", "cba" };
        yield return new object[] { "hello", "olleh" };
        yield return new object[] { "world", "dlrow" };
    }

    IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
}