Re-derive the floor-size test fixtures from the constants and move the ceiling to sample_bands.h

tests/test_keyboard_strip.cpp

@@ -8,7 +8,8 @@
 // octave boundaries and the 0..127 extremes; keyRect tiling and black-over-white overlap;
 // keyAtPoint resolving black-over-white by zone and missing off-band; the root affordance's
 // hit-to-marker round trip; resolveDragNote clamping a wandering pointer; noteName under the
-// C4 (MIDI 60) DAW convention; and the gutter pinned at the shipped default window size.
+// C4 (MIDI 60) DAW convention; the gutter at the sawtooth's maximum residue; and the gutter
+// pinned at the shipped default window size (derived from kEditorMinWidth/kEditorMinHeight).
 //
 // Client-pixel-only guarantee: every width swept below is a CLIENT-pixel width. Nothing in
 // the instrument implements IPlugViewContentScaleSupport, so if a host scales the plugin
@@ -280,28 +281,18 @@ static void testNoteNamesFollowTheC4Convention() {
     CHECK(noteName(500) == "G9");
 }
 
-// --- the gutter at the shipped default window size -----------------------------
+// --- the gutter at the sawtooth's maximum residue -------------------------------
 
 // The rule-based sweep above pins `margins == w % 75` and `leftMargin == margins/2` at every
-// width, but pins no concrete number — Daniel is making a visual call on the specific gutter
-// at the shipped default, and neither kPad nor the 840 default is covered by another test
-// firing if either ever changes. The strip is a sawtooth with period kStripWhiteKeyCount (75)
-// px of window width, and the shipped 840 default lands on residue 74 — the cycle's maximum:
-// one pixel of resize (840->841) collapses both gutters to zero and grows every white key
-// from 10px to 11px.
-static void testGutterAtTheShippedDefaultWindowSize() {
-    constexpr int kShippedDefaultWindowW = 840;   // editor_session.cpp's ViewRect default
-    constexpr int kShippedDefaultWindowH = 620;   // editor_session.cpp's ViewRect default
-    // Derive rootStrip's width the same way the shell does, through the real allocator +
-    // chrome layout, rather than re-deriving the inset formula — so a change to either one
-    // fails this test instead of silently moving the shipped gutter out from under it.
-    const SampleBands bands =
-        computeSampleBands(kShippedDefaultWindowW, kShippedDefaultWindowH, 0);
-    const ChromeRects chrome = chromeRects(bands.chrome, /*knobSize=*/24);
-    const int stripW = chrome.rootStrip.width;
-    CHECK(stripW == 824);
-
-    const StripLayout L = layoutStrip(stripW, 30);
+// width, but pins no concrete number. The strip is a sawtooth with period kStripWhiteKeyCount
+// (75) px of window width; 840 is an arbitrary but independently useful sample because it
+// lands on residue 74 — the cycle's maximum: one pixel of resize (840->841) collapses both
+// gutters to zero and grows every white key from 10px to 11px. Kept as a synthetic worst-case
+// sample; NOT tied to any shipped window size (see testGutterAtTheShippedDefaultWindowSize
+// below for that).
+static void testGutterAtTheSawtoothMaximumResidueWidth() {
+    constexpr int kSawtoothMaxResidueStripW = 824;  // an arbitrary width landing on residue 74
+    const StripLayout L = layoutStrip(kSawtoothMaxResidueStripW, 30);
     CHECK(L.whiteWidth == 10);
     const int margins = L.band.width - L.keys.width;
     CHECK(margins == 74);
@@ -309,6 +300,31 @@ static void testGutterAtTheShippedDefaultWindowSize() {
     CHECK(leftMargin == 37);
 }
 
+// --- the gutter at the shipped default window size -----------------------------
+
+// Daniel is making a visual call on the specific gutter at the shipped default; neither kPad
+// nor the floor is covered by another test firing if either ever changes. Derived from
+// kEditorMinWidth/kEditorMinHeight (editor_session.cpp's ViewRect default IS the floor) rather
+// than a hardcoded window size, so a floor change fails HERE instead of silently moving the
+// shipped gutter out from under it. The numbers below are today's floor (1190x680); re-derive
+// them by hand if the floor ever moves.
+static void testGutterAtTheShippedDefaultWindowSize() {
+    // Derive rootStrip's width the same way the shell does, through the real allocator +
+    // chrome layout, rather than re-deriving the inset formula.
+    const SampleBands bands = computeSampleBands(kEditorMinWidth, kEditorMinHeight, 0);
+    const ChromeRects chrome = chromeRects(bands.chrome, /*knobSize=*/24);
+    const int stripW = chrome.rootStrip.width;
+    CHECK(stripW == kEditorMinWidth - 2 * kPad);
+    CHECK(stripW == 1174);
+
+    const StripLayout L = layoutStrip(stripW, 30);
+    CHECK(L.whiteWidth == 15);
+    const int margins = L.band.width - L.keys.width;
+    CHECK(margins == 49);
+    const int leftMargin = L.keys.x - L.band.x;
+    CHECK(leftMargin == 24);
+}
+
 int main() {
     testLayoutFillsTheBandAndCentresTheKeys();
     testDegenerateSizesYieldNoKeys();
@@ -325,6 +341,7 @@ int main() {
     testHitTestingAKeyMarksThatSameKey();
     testDragTracksThePointerAndClampsWhenItWanders();
     testNoteNamesFollowTheC4Convention();
+    testGutterAtTheSawtoothMaximumResidueWidth();
     testGutterAtTheShippedDefaultWindowSize();
 
     if (g_fail == 0) {