params_valuetuples

example.cs

public class StringHash
{
    public static IEnumerable<(CultureInfo CultureInfo, CompareOptions CompareOptions)> GetOptions()
    {
        // Ordinal and OrdinalIgnoreCase use single execution path for all cultures, so we test it only for "en-US"
        yield return (new CultureInfo("en-US"), CompareOptions.Ordinal);
        yield return (new CultureInfo("en-US"), CompareOptions.OrdinalIgnoreCase);

        yield return (new CultureInfo("en-US"), CompareOptions.None);
        yield return (new CultureInfo("en-US"), CompareOptions.IgnoreCase);

        yield return (CultureInfo.InvariantCulture, CompareOptions.None);
        yield return (CultureInfo.InvariantCulture, CompareOptions.IgnoreCase);
    }

    [ParamsSource(nameof(GetOptions))]
    public (CultureInfo CultureInfo, CompareOptions CompareOptions) Options;

    [Params(
        128, // small input that fits into stack-allocated array https://github.com/dotnet/coreclr/blob/c6675ef2e22474d6222d054ae3d022c01eda9b6d/src/System.Private.CoreLib/shared/System/Globalization/CompareInfo.Unix.cs#L824
        1024 * 128)] // medium size input that fits into an array rented from ArrayPool.Shared without allocation
    public int Count { get; set; }

    private string _value;

    [GlobalSetup] // we are using part of Alice's Adventures in Wonderland text as test data
    public void Setup() => _value = new string(File.ReadAllText(CompressedFile.GetFilePath("alice29.txt")).Take(Count).ToArray());

    [Benchmark]
    public new void GetHashCode() => Options.CultureInfo.CompareInfo.GetHashCode(_value, Options.CompareOptions);
}