Phase S FB1 (r11): Sample-view recomposition — knob deck + elastic full-width hero + curve popup w/ right-click delete + post-mixer master gain (ComponentState v8)

tests/test_master_gain.cpp

@@ -0,0 +1,103 @@
+// Standalone tests for reasampler::vst::master_gain — no VST3, no REAPER, no framework. Same
+// fast assert loop as the sibling pure tests. Assert the FB1 post-mixer gain taper HARD:
+//
+//  * -inf bottom — norm 0 maps to -infinity dB and TRUE ZERO linear (silence, not an epsilon);
+//    linear <= 0 maps back to norm 0.
+//  * endpoints — norm 1 = +24 dB = masterGainMaxLinear() (~15.849); the finite floor at -60 dB.
+//  * unity — 0 dB round-trips exactly through norm<->dB<->linear (the knob's unity detent
+//    position 60/84 of the travel).
+//  * monotonicity — more norm never means less gain.
+//  * label — "-inf" at the bottom, signed one-decimal dB elsewhere.
+
+#include "../src/vst/master_gain.h"
+
+#include <cmath>
+#include <cstdio>
+#include <cstring>
+
+using namespace reasampler::vst;
+
+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 near(double a, double b, double eps = 1e-9) { return std::fabs(a - b) <= eps; }
+
+static void testBottomIsTrueSilence() {
+    CHECK(std::isinf(masterGainDbFromNorm(0.0)) && masterGainDbFromNorm(0.0) < 0.0);
+    CHECK(masterGainLinearFromNorm(0.0) == 0.0);  // exactly zero — the -inf contract
+    CHECK(masterGainNormFromLinear(0.0) == 0.0);
+    CHECK(masterGainNormFromLinear(-1.0) == 0.0);
+    CHECK(masterGainNormFromDb(-1e9) == 0.0);
+}
+
+static void testEndpoints() {
+    CHECK(near(masterGainDbFromNorm(1.0), kMasterGainMaxDb));
+    CHECK(near(masterGainLinearFromNorm(1.0), masterGainMaxLinear()));
+    CHECK(near(masterGainMaxLinear(), std::pow(10.0, 24.0 / 20.0)));
+    CHECK(near(masterGainNormFromDb(kMasterGainMaxDb), 1.0));
+    CHECK(near(masterGainNormFromLinear(masterGainMaxLinear()), 1.0));
+    // Out-of-range norms clamp.
+    CHECK(near(masterGainDbFromNorm(2.0), kMasterGainMaxDb));
+    CHECK(masterGainLinearFromNorm(-0.5) == 0.0);
+}
+
+static void testUnityRoundTrip() {
+    // 0 dB sits at norm -minDb/(maxDb-minDb) = 60/84 of the travel.
+    const double unityNorm = masterGainNormFromDb(0.0);
+    CHECK(near(unityNorm, 60.0 / 84.0, 1e-12));
+    CHECK(near(masterGainDbFromNorm(unityNorm), 0.0, 1e-9));
+    CHECK(near(masterGainLinearFromNorm(unityNorm), 1.0, 1e-9));
+    CHECK(near(masterGainNormFromLinear(1.0), unityNorm, 1e-9));
+}
+
+static void testNormLinearRoundTripAcrossTravel() {
+    for (int i = 1; i <= 20; ++i) {
+        const double norm = i / 20.0;
+        const double lin = masterGainLinearFromNorm(norm);
+        CHECK(lin > 0.0);
+        CHECK(near(masterGainNormFromLinear(lin), norm, 1e-9));
+    }
+}
+
+static void testMonotonic() {
+    double prev = -1.0;
+    for (int i = 0; i <= 100; ++i) {
+        const double lin = masterGainLinearFromNorm(i / 100.0);
+        CHECK(lin > prev);  // strictly increasing over the whole travel (0 at the bottom)
+        prev = lin;
+    }
+}
+
+static void testNonFiniteLinearClamps() {
+    CHECK(masterGainNormFromLinear(std::nan("")) == 0.0);
+    CHECK(near(masterGainNormFromLinear(1e9), 1.0));  // above the cap clamps to 1
+}
+
+static void testLabels() {
+    char buf[24];
+    formatMasterGainLabel(0.0, buf, sizeof(buf));
+    CHECK(std::strcmp(buf, "-inf") == 0);
+    formatMasterGainLabel(1.0, buf, sizeof(buf));
+    CHECK(std::strcmp(buf, "+24.0dB") == 0);
+    formatMasterGainLabel(masterGainNormFromDb(0.0), buf, sizeof(buf));
+    CHECK(std::strcmp(buf, "+0.0dB") == 0);
+    formatMasterGainLabel(masterGainNormFromDb(-12.0), buf, sizeof(buf));
+    CHECK(std::strcmp(buf, "-12.0dB") == 0);
+}
+
+int main() {
+    testBottomIsTrueSilence();
+    testEndpoints();
+    testUnityRoundTrip();
+    testNormLinearRoundTripAcrossTravel();
+    testMonotonic();
+    testNonFiniteLinearClamps();
+    testLabels();
+    if (g_fail) {
+        std::printf("%d FAILURE(S)\n", g_fail);
+        return 1;
+    }
+    std::printf("master_gain tests passed\n");
+    return 0;
+}