midigrid/test_lib.lua

-- Stub just enough of the reaper API to exercise the pure logic in the lib.
local ext = { root = "0", scale = "1" }
reaper = {
  GetExtState = function(_, k) return ext[k] or "" end,
  SetExtState = function(_, k, v) ext[k] = v end,
  APIExists = function() return false end,
  ShowConsoleMsg = function() end,
  SNM_GetIntConfigVar = function(_, d) return 1 end,
  GetCursorPosition = function() return 0 end,
  TimeMap_GetTimeSigAtTime = function() return 4, 4 end,
}

local G = dofile("D:\\code\\midigrid\\midigrid_lib.lua")

local fails = 0
local function eq(got, want, label)
  if got ~= want then
    print(("FAIL %s: got %s want %s"):format(label, tostring(got), tostring(want)))
    fails = fails + 1
  end
end

-- Note naming: with midioctoffs=1, note 60 reads as C5 (Reaper's default).
eq(G.noteName(60), "C5", "noteName 60")
eq(G.noteName(61), "C#5", "noteName 61")
eq(G.noteName(72), "C6", "noteName 72")
eq(G.noteName(48), "C4", "noteName 48")

-- C major: stepping up from C5 walks the scale, not semitones.
ext.root, ext.scale = "0", "1"
local p, seq = 60, {}
for _ = 1, 7 do p = G.scaleStep(p, 1); seq[#seq + 1] = p end
eq(table.concat(seq, ","), "62,64,65,67,69,71,72", "C major ascending")

p, seq = 60, {}
for _ = 1, 3 do p = G.scaleStep(p, -1); seq[#seq + 1] = p end
eq(table.concat(seq, ","), "59,57,55", "C major descending")

-- An off-scale note must not trap the cursor: C#5 in C major steps to D5.
eq(G.scaleStep(61, 1), 62, "off-scale up")
eq(G.scaleStep(61, -1), 60, "off-scale down")

-- Pentatonic skips more than a tone.
ext.scale = "10" -- major pentatonic
eq(G.scaleStep(60, 1), 62, "pentatonic C->D")
eq(G.scaleStep(64, 1), 67, "pentatonic E->G")

-- Chromatic behaves like plain semitones.
ext.scale = "14"
eq(G.scaleStep(60, 1), 61, "chromatic up")

-- Root transposition: A natural minor.
ext.root, ext.scale = "9", "2"
eq(G.inScale(69), true, "A in A minor")
eq(G.inScale(70), false, "A# not in A minor")
eq(G.scaleName(), "A natural minor", "scale name")

-- Range clamping at the extremes of the MIDI range.
ext.root, ext.scale = "0", "1"
eq(G.scaleStep(127, 1), nil, "top of range")
eq(G.scaleStep(0, -1), nil, "bottom of range")

-- Grid labels in 4/4: one bar is 4 QN.
eq(G.gridLabel(4), "1 bar", "grid 1 bar")
eq(G.gridLabel(8), "2 bars", "grid 2 bars")
eq(G.gridLabel(1), "1/4", "grid quarter")
eq(G.gridLabel(0.25), "1/16", "grid sixteenth")
eq(G.gridLabel(0.5), "1/8", "grid eighth")

-- Diatonic chords: stacking scale thirds must yield the right quality for
-- each degree, without any chord-quality table.
ext.root, ext.scale = "0", "1" -- C major
eq(table.concat(G.chordPitches(60, 3), ","), "60,64,67", "C major triad")
eq(table.concat(G.chordPitches(62, 3), ","), "62,65,69", "D minor triad")
eq(table.concat(G.chordPitches(71, 3), ","), "71,74,77", "B diminished triad")
eq(table.concat(G.chordPitches(60, 4), ","), "60,64,67,71", "C major seventh")
eq(table.concat(G.chordPitches(67, 4), ","), "67,71,74,77", "G dominant seventh")

-- A minor triad from its own root.
ext.root, ext.scale = "9", "2"
eq(table.concat(G.chordPitches(69, 3), ","), "69,72,76", "A minor triad")

-- Running off the top of the MIDI range yields nil rather than a partial chord.
ext.root, ext.scale = "0", "1"
eq(G.chordPitches(127, 3), nil, "chord past top of range")

print(fails == 0 and "ALL PASS" or (fails .. " FAILURES"))