reasampler/tests/test_render_window.cpp

// Standalone tests for reasampler::render_window — no REAPER, no framework.
// Covers the bounds-equality number (a window's exact frame count at the project
// rate) and the predicate that decides whether REAPER's selected-items render
// source can express a requested window at all.

#include "../src/core/capture/render_window.h"

#include <cstdio>

using namespace reasampler::capture;

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

// --- frameCountFor: the bounds equality, stated as a number ------------------

static void testFrameCountIsExactNotRounded() {
    // A 1.5 s window at 48 kHz is exactly 72000 frames — the number a capture of
    // that range must produce. No rounding slack in either direction.
    CHECK(frameCountFor(2.0, 3.5, 48000) == 72000);
    // The same duration at a different offset still counts the same frames when
    // both edges are frame-aligned.
    CHECK(frameCountFor(10.0, 11.5, 48000) == 72000);
    // 44.1 kHz: 0.5 s = 22050 frames.
    CHECK(frameCountFor(1.0, 1.5, 44100) == 22050);
}

static void testFrameCountIsADifferenceOfIndicesNotADuration() {
    // Both edges land mid-frame at 100 Hz (0.005 s = half a frame). Rounding the
    // DURATION would give 1 frame; rounding each EDGE gives 0.005 -> frame 1 and
    // 0.015 -> frame 2, i.e. 1 frame. Shift the window so the edges round apart
    // and the count changes — the property that makes this a window, not a length.
    CHECK(frameCountFor(0.005, 0.015, 100) == 1);
    CHECK(frameCountFor(0.004, 0.016, 100) == 2);
}

static void testFrameCountRefusesEmptyInvertedAndUnknownRate() {
    CHECK(frameCountFor(3.0, 3.0, 48000) == 0);   // empty
    CHECK(frameCountFor(3.0, 1.0, 48000) == 0);   // inverted
    CHECK(frameCountFor(1.0, 2.0, 0)     == 0);   // rate unknown
    CHECK(frameCountFor(1.0, 2.0, -1)    == 0);   // rate nonsensical
}

// --- itemExtentPrintsWindow: can the selected-items source express this? -----

static void testRangeInsideItemCannotBeExpressed() {
    // The defect this whole module exists for: a 1 s selection inside a 30 s item.
    // The selected-items source would print the item's 30 s, not the 1 s asked for,
    // so the capture must NOT take that path.
    CHECK(!itemExtentPrintsWindow(5.0, 6.0, /*item*/ 0.0, 30.0, 48000));
}

static void testRangeWiderThanItemCannotBeExpressedEither() {
    // The same violation in the other direction: a 10 s selection over a 6 s item
    // would print 6 s. Under-printing is a bounds violation exactly as much as
    // over-printing is.
    CHECK(!itemExtentPrintsWindow(0.0, 10.0, /*item*/ 2.0, 8.0, 48000));
}

static void testEachEdgeAloneDisqualifies() {
    // Matching start, drifting end.
    CHECK(!itemExtentPrintsWindow(2.0, 8.0, 2.0, 9.0, 48000));
    // Matching end, drifting start.
    CHECK(!itemExtentPrintsWindow(2.0, 8.0, 1.0, 8.0, 48000));
}

static void testExtentEqualToWindowIsExpressible() {
    // The regression floor: a capture whose range IS the item's extent keeps the
    // selected-items render, byte-identical to what it produces today.
    CHECK(itemExtentPrintsWindow(2.0, 8.0, 2.0, 8.0, 48000));
}

static void testSubFrameDriftStillPrintsTheSameFrames() {
    // A time selection snapped a fraction of a sample off the item edge prints the
    // identical frames, so it must NOT be pushed onto the time-bounded path — that
    // would swap the render mechanism under a capture that was already exact.
    const double eighthOfAFrameAt48k = 1.0 / (48000.0 * 8.0);
    CHECK(itemExtentPrintsWindow(2.0 + eighthOfAFrameAt48k, 8.0 - eighthOfAFrameAt48k,
                                 2.0, 8.0, 48000));
    // A full frame of drift is a real difference and must disqualify.
    const double oneFrameAt48k = 1.0 / 48000.0;
    CHECK(!itemExtentPrintsWindow(2.0 + oneFrameAt48k, 8.0, 2.0, 8.0, 48000));
}

static void testUnknownRateFallsBackToExactEquality() {
    // With no project rate there is no frame grid to compare on. Exact equality
    // still recognizes the regression floor...
    CHECK(itemExtentPrintsWindow(2.0, 8.0, 2.0, 8.0, 0));
    // ...and anything else takes the time-bounded render, which honors the request
    // whatever the rate turns out to be.
    const double eighthOfAFrameAt48k = 1.0 / (48000.0 * 8.0);
    CHECK(!itemExtentPrintsWindow(2.0 + eighthOfAFrameAt48k, 8.0, 2.0, 8.0, 0));
    CHECK(!itemExtentPrintsWindow(5.0, 6.0, 0.0, 30.0, 0));
}

static void testMultiItemUnionExtent() {
    // Two items spanning 1..4 and 6..9 present a 1..9 union extent to the render.
    // A selection over the whole union is expressible; one over only the first
    // item's half is not.
    CHECK(itemExtentPrintsWindow(1.0, 9.0, 1.0, 9.0, 48000));
    CHECK(!itemExtentPrintsWindow(1.0, 4.0, 1.0, 9.0, 48000));
}

int main() {
    testFrameCountIsExactNotRounded();
    testFrameCountIsADifferenceOfIndicesNotADuration();
    testFrameCountRefusesEmptyInvertedAndUnknownRate();
    testRangeInsideItemCannotBeExpressed();
    testRangeWiderThanItemCannotBeExpressedEither();
    testEachEdgeAloneDisqualifies();
    testExtentEqualToWindowIsExpressible();
    testSubFrameDriftStillPrintsTheSameFrames();
    testUnknownRateFallsBackToExactEquality();
    testMultiItemUnionExtent();

    if (g_fail) { std::printf("%d check(s) FAILED\n", g_fail); return 1; }
    std::printf("render_window: all checks passed\n");
    return 0;
}