FastRng/FastRngTests/Distributions/ExponentialLa5.cs

using System;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Threading.Tasks;
using FastRng;
using NUnit.Framework;

namespace FastRngTests.Distributions;

[ExcludeFromCodeCoverage]
public class ExponentialLa5
{
    [Test]
    [Category(TestCategories.COVER)]
    [Category(TestCategories.NORMAL)]
    public async Task TestExponentialDistribution01()
    {
        using var rng = new MultiThreadedRng<float>();
        var dist = new FastRng.Distributions.ExponentialLa5<float>(rng);
        var fqa = new FrequencyAnalysis();

        for (var n = 0; n < 100_000; n++)
            fqa.CountThis(await dist.NextNumber());
            
        var result = fqa.NormalizeAndPlotEvents(TestContext.WriteLine);

        Assert.That(result[0], Is.EqualTo(1.0002177398625f).Within(0.05f));
        Assert.That(result[1], Is.EqualTo(0.951436545064811f).Within(0.05f));
        Assert.That(result[2], Is.EqualTo(0.905034437210948f).Within(0.05f));
            
        Assert.That(result[21], Is.EqualTo(0.35001394450853f).Within(0.05f));
        Assert.That(result[22], Is.EqualTo(0.332943563002074f).Within(0.05f));
        Assert.That(result[23], Is.EqualTo(0.31670571382568f).Within(0.05f));
            
        Assert.That(result[50], Is.EqualTo(0.082102871800213f).Within(0.01f));
            
        Assert.That(result[75], Is.EqualTo(0.023522866606758f).Within(0.01f));
        Assert.That(result[85], Is.EqualTo(0.014267339801329f).Within(0.01f));
        Assert.That(result[90], Is.EqualTo(0.011111415409621f).Within(0.01f));
            
        Assert.That(result[97], Is.EqualTo(0.007830082099077f).Within(0.008f));
        Assert.That(result[98], Is.EqualTo(0.007448204488898f).Within(0.008f));
        Assert.That(result[99], Is.EqualTo(0.007084951269538f).Within(0.008f));
    }
        
    [Test]
    [Category(TestCategories.COVER)]
    [Category(TestCategories.NORMAL)]
    public async Task TestExponentialGeneratorWithRange01()
    {
        using var rng = new MultiThreadedRng<float>();
        var dist = new FastRng.Distributions.ExponentialLa5<float>(rng);
        var samples = new float[1_000];
        for (var n = 0; n < samples.Length; n++)
            samples[n] = await dist.NextNumber(-1.0f, 1.0f);
            
        Assert.That(samples.Min(), Is.GreaterThanOrEqualTo(-1.0f), "Min out of range");
        Assert.That(samples.Max(), Is.LessThanOrEqualTo(1.0f), "Max out of range");
    }
        
    [Test]
    [Category(TestCategories.COVER)]
    [Category(TestCategories.NORMAL)]
    public async Task TestExponentialGeneratorWithRange02()
    {
        using var rng = new MultiThreadedRng<float>();
        var dist = new FastRng.Distributions.ExponentialLa5<float>(rng);
        var samples = new float[1_000];
        for (var n = 0; n < samples.Length; n++)
            samples[n] = await dist.NextNumber(0.0f, 1.0f);
            
        Assert.That(samples.Min(), Is.GreaterThanOrEqualTo(0.0f), "Min is out of range");
        Assert.That(samples.Max(), Is.LessThanOrEqualTo(1.0f), "Max is out of range");
    }

    [Test]
    [Category(TestCategories.COVER)]
    [Category(TestCategories.NORMAL)]
    public void NoRandomNumberGenerator01()
    {
        Assert.Throws<ArgumentNullException>(() => new FastRng.Distributions.ExponentialLa5<float>(null));
    }
}