Add pitch model octave-normalization tests

tests/test_pitch_model_additional.py

@@ -0,0 +1,81 @@
+"""Focused tests for ``iav.pitch_model`` octave normalisation in spelling."""
+
+from __future__ import annotations
+
+import pytest
+
+from iav.pitch_model import chromatic_midi_float, spelled_note_from_chromatic_midi
+
+
+def _assert_roundtrip(midi: float) -> None:
+    spelling = spelled_note_from_chromatic_midi(midi)
+    assert chromatic_midi_float(*spelling) == pytest.approx(midi)
+
+
+def test_spelled_note_in_octave_middle_c_unchanged():
+    assert spelled_note_from_chromatic_midi(60.0) == ("C", 0.0, 4)
+    _assert_roundtrip(60.0)
+
+
+def test_downward_octave_wrap_c4_minus_one_semitone():
+    midi = chromatic_midi_float("C", 0.0, 4) - 1.0
+    assert spelled_note_from_chromatic_midi(midi) == ("B", 0.0, 3)
+    _assert_roundtrip(midi)
+
+
+def test_upward_octave_wrap_b4_plus_one_semitone():
+    midi = chromatic_midi_float("B", 0.0, 4) + 1.0
+    assert spelled_note_from_chromatic_midi(midi) == ("C", 0.0, 5)
+    _assert_roundtrip(midi)
+
+
+def test_multiple_octave_downward_wrap():
+    midi = chromatic_midi_float("C", 0.0, 4) - 13.0
+    assert spelled_note_from_chromatic_midi(midi) == ("B", 0.0, 2)
+    _assert_roundtrip(midi)
+
+    midi_two_octaves = chromatic_midi_float("C", 0.0, 4) - 24.0
+    assert spelled_note_from_chromatic_midi(midi_two_octaves) == ("C", 0.0, 2)
+    _assert_roundtrip(midi_two_octaves)
+
+
+def test_multiple_octave_upward_wrap():
+    midi = chromatic_midi_float("B", 0.0, 4) + 13.0
+    assert spelled_note_from_chromatic_midi(midi) == ("C", 0.0, 6)
+    _assert_roundtrip(midi)
+
+    midi_two_octaves = chromatic_midi_float("C", 0.0, 4) + 24.0
+    assert spelled_note_from_chromatic_midi(midi_two_octaves) == ("C", 0.0, 6)
+    _assert_roundtrip(midi_two_octaves)
+
+
+def test_boundary_rem_zero_does_not_change_octave():
+    assert spelled_note_from_chromatic_midi(60.0) == ("C", 0.0, 4)
+    assert spelled_note_from_chromatic_midi(72.0) == ("C", 0.0, 5)
+
+
+def test_boundary_rem_just_below_twelve_stays_in_octave():
+    midi = chromatic_midi_float("B", 0.0, 4) + 0.999999999
+    spelling = spelled_note_from_chromatic_midi(midi)
+    assert spelling[0] == "B"
+    assert spelling[2] == 4
+    _assert_roundtrip(midi)
+
+
+def test_boundary_twelfth_semitone_crosses_to_next_octave():
+    midi = chromatic_midi_float("B", 0.0, 4) + 1.0
+    assert spelled_note_from_chromatic_midi(midi) == ("C", 0.0, 5)
+
+
+def test_defensive_downward_rem_loop_on_large_midi_float():
+    """Floating-point residue can fall below zero at extreme magnitudes."""
+    midi = float(2**56 - 5)
+    spelling = spelled_note_from_chromatic_midi(midi)
+    assert spelling == ("E", 0.0, 6004799503160659)
+
+
+def test_defensive_upward_rem_loop_on_large_midi_float():
+    """Floating-point residue can reach twelve or more at extreme magnitudes."""
+    midi = float(2**57 - 41)
+    spelling = spelled_note_from_chromatic_midi(midi)
+    assert spelling == ("E", 0.0, 12009599006321318)