meeting-assistant/MeetingAssistant.Tests/ResemblyzerVoiceClusterMatcherTests.cs

using MeetingAssistant;
using MeetingAssistant.Speakers;
using Microsoft.Extensions.Logging.Abstractions;

namespace MeetingAssistant.Tests;

public sealed class ResemblyzerVoiceClusterMatcherTests
{
    [Fact]
    public void CoherentSimilarClusterSelectsUnambiguousIdentity()
    {
        var matcher = CreateMatcher();
        var query = Enumerable.Range(0, 5)
            .Select(index => UnitVector(0, secondaryDimension: index + 2, secondaryValue: 0.05f))
            .ToList();
        var candidates = new[]
        {
            new ResemblyzerVoiceVectorCandidate(42, [UnitVector(0), UnitVector(0, 10, 0.02f)]),
            new ResemblyzerVoiceVectorCandidate(77, [UnitVector(1), UnitVector(1, 11, 0.02f)])
        };

        var result = matcher.Match(query, candidates);

        Assert.True(result.Accepted);
        Assert.Equal(42, result.IdentityId);
        Assert.True(result.Cohesion >= 0.99);
        Assert.True(result.BestSimilarity >= 0.99);
        Assert.True(result.RunnerUpSimilarity < 0.1);
    }

    [Fact]
    public void FourVectorsDoNotTriggerAutomaticMatching()
    {
        var result = CreateMatcher().Match(
            Enumerable.Repeat(UnitVector(0), 4).ToList(),
            [new ResemblyzerVoiceVectorCandidate(42, [UnitVector(0)])]);

        Assert.False(result.Accepted);
        Assert.Contains("4/5", result.Reason);
    }

    [Fact]
    public void IncoherentClusterIsRejectedBeforeIdentityScoring()
    {
        var result = CreateMatcher().Match(
            Enumerable.Range(0, 5).Select(index => UnitVector(index)).ToList(),
            [new ResemblyzerVoiceVectorCandidate(42, [UnitVector(0)])]);

        Assert.False(result.Accepted);
        Assert.Contains("cohesion", result.Reason);
        Assert.Null(result.BestSimilarity);
    }

    [Fact]
    public void SimilarityBelowThresholdIsRejected()
    {
        var result = CreateMatcher().Match(
            Enumerable.Repeat(UnitVector(0), 5).ToList(),
            [new ResemblyzerVoiceVectorCandidate(42, [UnitVector(1)])]);

        Assert.False(result.Accepted);
        Assert.Contains("best similarity", result.Reason);
        Assert.Equal(0, result.BestSimilarity);
    }

    [Fact]
    public void SimilarCandidatesWithinMarginAreRejected()
    {
        var result = CreateMatcher().Match(
            Enumerable.Repeat(UnitVector(0), 5).ToList(),
            [
                new ResemblyzerVoiceVectorCandidate(42, [UnitVector(0)]),
                new ResemblyzerVoiceVectorCandidate(77, [UnitVector(0, 1, 0.01f)])
            ]);

        Assert.False(result.Accepted);
        Assert.Contains("margin", result.Reason);
        Assert.NotNull(result.RunnerUpSimilarity);
    }

    [Fact]
    public void InvalidStoredCandidateDoesNotAbortScoringOtherIdentities()
    {
        var result = CreateMatcher().Match(
            Enumerable.Repeat(UnitVector(0), 5).ToList(),
            [
                new ResemblyzerVoiceVectorCandidate(13, [new float[256]]),
                new ResemblyzerVoiceVectorCandidate(42, [UnitVector(0)])
            ]);

        Assert.True(result.Accepted);
        Assert.Equal(42, result.IdentityId);
    }

    private static ResemblyzerVoiceClusterMatcher CreateMatcher()
    {
        return new ResemblyzerVoiceClusterMatcher(
            new ResemblyzerSpeakerRecognitionOptions
            {
                RequiredVectorsPerSpeaker = 5,
                MinimumClusterCohesion = 0.75,
                MinimumIdentitySimilarity = 0.75,
                MinimumSimilarityMargin = 0.05
            },
            NullLogger<ResemblyzerVoiceClusterMatcher>.Instance);
    }

    private static float[] UnitVector(
        int primaryDimension,
        int? secondaryDimension = null,
        float secondaryValue = 0)
    {
        var vector = new float[256];
        vector[primaryDimension] = 1;
        if (secondaryDimension is { } dimension)
        {
            vector[dimension] = secondaryValue;
        }

        return vector;
    }
}