meeting-assistant/MeetingAssistant.Tests/SpeakerSampleSpanSelectorTests.cs

using MeetingAssistant.Speakers;
using MeetingAssistant.Transcription;

namespace MeetingAssistant.Tests;

public sealed class SpeakerSampleSpanSelectorTests
{
    [Fact]
    public void SelectBestSameSpeakerSpanCombinesLinesAndCapsTheClip()
    {
        var span = SpeakerSampleSpanSelector.SelectBestSameSpeakerSpan(
            [
                Segment(0, 4),
                Segment(7, 13),
                Segment(20, 70)
            ],
            "Guest01",
            TimeSpan.FromSeconds(10),
            TimeSpan.FromSeconds(60));

        Assert.Equal(3, span.Count);
        Assert.Equal(TimeSpan.Zero, span[0].Start);
        Assert.Equal(TimeSpan.FromSeconds(60), span[^1].End);
        Assert.Equal(TimeSpan.FromSeconds(60), SpeakerSampleSpanSelector.SpanDuration(span));
    }

    [Fact]
    public void SelectBestSameSpeakerSpanDoesNotCountProviderPausesAsSpeakerAudio()
    {
        var span = SpeakerSampleSpanSelector.SelectBestSameSpeakerSpan(
            [
                Segment(0, 4),
                Segment(20, 25)
            ],
            "Guest01",
            TimeSpan.FromSeconds(10),
            TimeSpan.FromSeconds(60));

        Assert.Empty(span);
    }

    [Fact]
    public void SelectBestSameSpeakerSpansReturnsDistinctMinimumLengthSamples()
    {
        var segments = Enumerable.Range(0, 6)
            .Select(index => new TranscriptionSegment(
                TimeSpan.FromSeconds(index * 10),
                TimeSpan.FromSeconds((index + 1) * 10),
                "Guest01",
                $"segment {index} has enough words"))
            .ToList();

        var spans = SpeakerSampleSpanSelector.SelectBestSameSpeakerSpans(
            segments,
            "Guest01",
            TimeSpan.FromSeconds(10),
            TimeSpan.FromSeconds(60),
            maxSpans: 5);

        Assert.Equal(5, spans.Count);
        Assert.All(spans, span => Assert.True(SpeakerSampleSpanSelector.SpanDuration(span) >= TimeSpan.FromSeconds(10)));
        Assert.All(
            spans.Zip(spans.Skip(1)),
            pair => Assert.True(pair.First[^1].End <= pair.Second[0].Start));
    }

    [Fact]
    public void SelectBestSameSpeakerSpansSkipsSegmentsThatOverlapACompletedSample()
    {
        var spans = SpeakerSampleSpanSelector.SelectBestSameSpeakerSpans(
            [
                Segment(0, 10),
                Segment(9, 19),
                Segment(20, 30)
            ],
            "Guest01",
            TimeSpan.FromSeconds(10),
            TimeSpan.FromSeconds(60),
            maxSpans: 5);

        Assert.Equal(2, spans.Count);
        Assert.Equal(TimeSpan.Zero, spans[0][0].Start);
        Assert.Equal(TimeSpan.FromSeconds(20), spans[1][0].Start);
    }

    [Fact]
    public void SelectBestSameSpeakerSpansCombinesConsecutiveLinesAcrossProviderPauses()
    {
        var spans = SpeakerSampleSpanSelector.SelectBestSameSpeakerSpans(
            [
                Segment(0, 4),
                Segment(7, 13)
            ],
            "Guest01",
            TimeSpan.FromSeconds(10),
            TimeSpan.FromSeconds(60),
            maxSpans: 5);

        var span = Assert.Single(spans);
        Assert.Equal(TimeSpan.Zero, span[0].Start);
        Assert.Equal(TimeSpan.FromSeconds(13), span[^1].End);
    }

    [Fact]
    public void SelectBestSameSpeakerSpansDoesNotCountProviderPausesAsSpeakerAudio()
    {
        var spans = SpeakerSampleSpanSelector.SelectBestSameSpeakerSpans(
            [
                Segment(0, 4),
                Segment(20, 25)
            ],
            "Guest01",
            TimeSpan.FromSeconds(10),
            TimeSpan.FromSeconds(60),
            maxSpans: 5);

        Assert.Empty(spans);
    }

    [Fact]
    public void SelectBestSameSpeakerSpansCapsFinalizedSamplesAtConfiguredMaximumDuration()
    {
        var spans = SpeakerSampleSpanSelector.SelectBestSameSpeakerSpans(
            [Segment(0, 70)],
            "Guest01",
            TimeSpan.FromSeconds(10),
            TimeSpan.FromSeconds(60),
            maxSpans: 5);

        var span = Assert.Single(spans);
        Assert.Equal(TimeSpan.FromSeconds(60), SpeakerSampleSpanSelector.SpanDuration(span));
    }

    private static TranscriptionSegment Segment(double start, double end)
    {
        return new TranscriptionSegment(
            TimeSpan.FromSeconds(start),
            TimeSpan.FromSeconds(end),
            "Guest01",
            "enough words for this segment");
    }
}