PerformanceTestBaseTDelegate, TResult Class

public abstract class PerformanceTestBase<TDelegate, TResult> : PerformanceTestBase
where TDelegate : Delegate

public class RandomizedPerformanceTest<T> : PerformanceTestBase<Func<Random, T>, T>
{
    private Random random;

    // a fix seed can be specified when initializing the test
    public int Seed { get; set; }

    protected override T Invoke(Func<Random, T> del) => del.Invoke(random);

    // resetting the random instance with the specified seed before executing each case
    protected override void OnBeforeCase() => random = new Random(Seed);
}

new RandomizedPerformanceTest<string> { Seed = 0, Iterations = 1_000_000 }
    .AddCase(rnd => rnd.NextEnum<ConsoleColor>().ToString(), "Enum.ToString")
    .AddCase(rnd => Enum<ConsoleColor>.ToString(rnd.NextEnum<ConsoleColor>()), "Enum<TEnum>.ToString")
    .DoTest()
    .DumpResults(Console.Out);