reasampler/tests/test_musical_division.cpp

// Standalone tests for reasampler::instrument::note::musical_division — no VST3, no REAPER,
// no framework. Same fast assert loop as the sibling pure tests.
//
// Covers: the beat length of all 39 divisions against a literal rung table (NOT the module's
// own exponent formula); the 1/64 and 64/1 extremes; the four named example divisions; the
// label notation; picker order and index round-trip; off-ladder clamping.

#include "../src/core/instrument/note/musical_division.h"

#include <cstdio>

using namespace reasampler::instrument::note;

static int g_fail = 0;
#define CHECK(cond) do { if(!(cond)) { \
    std::printf("FAIL line %d: %s\n", __LINE__, #cond); ++g_fail; } } while(0)

static bool almostEqual(double a, double b) {
    const double d = a - b;
    return (d < 0 ? -d : d) < 1e-12;
}

// Length in beats (quarter notes) of each straight rung, written out rather than computed,
// so a broken exponent formula cannot agree with its own mistake.
static const double kStraightBeats[kRungCount] = {
    0.0625,  // 1/64
    0.125,   // 1/32
    0.25,    // 1/16
    0.5,     // 1/8
    1.0,     // 1/4
    2.0,     // 1/2
    4.0,     // 1/1
    8.0,     // 2/1
    16.0,    // 4/1
    32.0,    // 8/1
    64.0,    // 16/1
    128.0,   // 32/1
    256.0,   // 64/1
};

static const char* const kStraightLabels[kRungCount] = {
    "1/64", "1/32", "1/16", "1/8", "1/4", "1/2", "1/1",
    "2/1", "4/1", "8/1", "16/1", "32/1", "64/1",
};

// --- The ladder ---------------------------------------------------------------

static void testLadderSpansSixtyfourthToSixtyFourWhole() {
    CHECK(kRungCount == 13);
    CHECK(kDivisionCount == 39);
    CHECK(divisionLabel(divisionAt(0)) == "1/64");
    CHECK(divisionLabel(divisionAt(kDivisionCount - 1)) == "64/1t");
}

static void testEveryStraightRungHasItsWrittenBeatLength() {
    for (int rung = 0; rung < kRungCount; ++rung) {
        const Division d = makeDivision(kMinQuarterExponent + rung, DivisionModifier::Straight);
        CHECK(almostEqual(divisionBeats(d), kStraightBeats[rung]));
        CHECK(divisionLabel(d) == kStraightLabels[rung]);
    }
}

static void testDottedIsHalfAgainAndTripletIsTwoThirds() {
    for (int rung = 0; rung < kRungCount; ++rung) {
        const int e = kMinQuarterExponent + rung;
        CHECK(almostEqual(divisionBeats(makeDivision(e, DivisionModifier::Dotted)),
                   kStraightBeats[rung] * 1.5));
        CHECK(almostEqual(divisionBeats(makeDivision(e, DivisionModifier::Triplet)),
                   kStraightBeats[rung] * 2.0 / 3.0));
    }
}

static void testExtremes() {
    // 1/64 straight is the shortest rung; 64/1 straight is the longest.
    CHECK(almostEqual(divisionBeats(makeDivision(kMinQuarterExponent, DivisionModifier::Straight)),
               0.0625));
    CHECK(almostEqual(divisionBeats(makeDivision(kMaxQuarterExponent, DivisionModifier::Straight)),
               256.0));
    // The dotted 64/1 is the single longest programmable note.
    CHECK(almostEqual(divisionBeats(makeDivision(kMaxQuarterExponent, DivisionModifier::Dotted)),
               384.0));
    // The 1/64 triplet is the shortest.
    CHECK(almostEqual(divisionBeats(makeDivision(kMinQuarterExponent, DivisionModifier::Triplet)),
               0.0625 * 2.0 / 3.0));
}

// --- The four named examples --------------------------------------------------

static void testNamedExamples() {
    // 1/8. — an eighth is half a beat, dotted is three quarters of one.
    const Division dottedEighth = makeDivision(-1, DivisionModifier::Dotted);
    CHECK(almostEqual(divisionBeats(dottedEighth), 0.75));
    CHECK(divisionLabel(dottedEighth) == "1/8.");

    // 1/4t — a quarter is one beat, the triplet is two thirds of one.
    const Division quarterTriplet = makeDivision(0, DivisionModifier::Triplet);
    CHECK(almostEqual(divisionBeats(quarterTriplet), 2.0 / 3.0));
    CHECK(divisionLabel(quarterTriplet) == "1/4t");

    // 1/16 — a quarter of a beat.
    const Division sixteenth = makeDivision(-2, DivisionModifier::Straight);
    CHECK(almostEqual(divisionBeats(sixteenth), 0.25));
    CHECK(divisionLabel(sixteenth) == "1/16");

    // 4/1 — four whole notes, sixteen beats.
    const Division fourWhole = makeDivision(4, DivisionModifier::Straight);
    CHECK(almostEqual(divisionBeats(fourWhole), 16.0));
    CHECK(divisionLabel(fourWhole) == "4/1");
}

// --- Picker order -------------------------------------------------------------

static void testPickerOrderIsShortestFirst() {
    // Straight lengths ascend across rungs; within a rung the order is straight, dotted,
    // triplet (so the index is not itself sorted by duration — only the rungs are).
    for (int rung = 1; rung < kRungCount; ++rung) {
        const double prev = divisionBeats(divisionAt((rung - 1) * kModifierCount));
        const double here = divisionBeats(divisionAt(rung * kModifierCount));
        CHECK(here > prev);
    }
    CHECK(divisionAt(0) == makeDivision(kMinQuarterExponent, DivisionModifier::Straight));
    CHECK(divisionAt(1) == makeDivision(kMinQuarterExponent, DivisionModifier::Dotted));
    CHECK(divisionAt(2) == makeDivision(kMinQuarterExponent, DivisionModifier::Triplet));
}

static void testIndexRoundTripsOverTheWholeSet() {
    for (int i = 0; i < kDivisionCount; ++i) {
        CHECK(divisionIndex(divisionAt(i)) == i);
    }
}

static void testEverySetMemberIsDistinct() {
    // No two indices name the same division, so the picker offers 39 real choices.
    for (int i = 0; i < kDivisionCount; ++i) {
        for (int j = i + 1; j < kDivisionCount; ++j) {
            CHECK(divisionAt(i) != divisionAt(j));
        }
    }
}

// --- Clamping -----------------------------------------------------------------

static void testOffLadderExponentClampsToTheNearestRung() {
    CHECK(makeDivision(-99, DivisionModifier::Straight)
          == makeDivision(kMinQuarterExponent, DivisionModifier::Straight));
    CHECK(makeDivision(99, DivisionModifier::Triplet)
          == makeDivision(kMaxQuarterExponent, DivisionModifier::Triplet));
    // A record carrying an off-ladder exponent still resolves to a real length.
    Division corrupt;
    corrupt.quarterExponent = 120;
    CHECK(almostEqual(divisionBeats(corrupt), 256.0));
}

static void testOutOfRangeIndexClampsIntoTheSet() {
    CHECK(divisionAt(-1) == divisionAt(0));
    CHECK(divisionAt(kDivisionCount) == divisionAt(kDivisionCount - 1));
}

int main() {
    testLadderSpansSixtyfourthToSixtyFourWhole();
    testEveryStraightRungHasItsWrittenBeatLength();
    testDottedIsHalfAgainAndTripletIsTwoThirds();
    testExtremes();

    testNamedExamples();

    testPickerOrderIsShortestFirst();
    testIndexRoundTripsOverTheWholeSet();
    testEverySetMemberIsDistinct();

    testOffLadderExponentClampsToTheNearestRung();
    testOutOfRangeIndexClampsIntoTheSet();

    if (g_fail == 0) std::printf("musical_division: all tests passed\n");
    else std::printf("musical_division: %d FAILED\n", g_fail);
    return g_fail == 0 ? 0 : 1;
}