test_midi_diff.py
python
| 1 | """Tests for muse.plugins.music.midi_diff — Myers LCS on MIDI note sequences. |
| 2 | |
| 3 | Covers: |
| 4 | - NoteKey extraction from MIDI bytes. |
| 5 | - LCS edit script correctness (keep/insert/delete). |
| 6 | - LCS minimality (length of keep steps == LCS length). |
| 7 | - diff_midi_notes() produces correct StructuredDelta. |
| 8 | - Content IDs are deterministic and unique per note. |
| 9 | - Human-readable summaries and content_summary strings. |
| 10 | """ |
| 11 | from __future__ import annotations |
| 12 | |
| 13 | import io |
| 14 | import struct |
| 15 | |
| 16 | import mido |
| 17 | import pytest |
| 18 | |
| 19 | from muse.plugins.music.midi_diff import ( |
| 20 | NoteKey, |
| 21 | diff_midi_notes, |
| 22 | extract_notes, |
| 23 | lcs_edit_script, |
| 24 | ) |
| 25 | |
| 26 | |
| 27 | # --------------------------------------------------------------------------- |
| 28 | # MIDI builder helpers |
| 29 | # --------------------------------------------------------------------------- |
| 30 | |
| 31 | def _build_midi(notes: list[tuple[int, int, int, int]]) -> bytes: |
| 32 | """Build a minimal type-0 MIDI file from (pitch, velocity, start, duration) tuples. |
| 33 | |
| 34 | All values use ticks_per_beat=480. Produces valid mido-parseable MIDI bytes. |
| 35 | """ |
| 36 | mid = mido.MidiFile(type=0, ticks_per_beat=480) |
| 37 | track = mido.MidiTrack() |
| 38 | mid.tracks.append(track) |
| 39 | |
| 40 | # Collect all events sorted by tick. |
| 41 | events: list[tuple[int, str, int, int]] = [] # (tick, type, note, velocity) |
| 42 | for pitch, velocity, start, duration in notes: |
| 43 | events.append((start, "note_on", pitch, velocity)) |
| 44 | events.append((start + duration, "note_off", pitch, 0)) |
| 45 | |
| 46 | events.sort(key=lambda e: e[0]) |
| 47 | |
| 48 | prev_tick = 0 |
| 49 | for tick, msg_type, note, vel in events: |
| 50 | delta = tick - prev_tick |
| 51 | track.append(mido.Message(msg_type, note=note, velocity=vel, time=delta)) |
| 52 | prev_tick = tick |
| 53 | |
| 54 | track.append(mido.MetaMessage("end_of_track", time=0)) |
| 55 | |
| 56 | buf = io.BytesIO() |
| 57 | mid.save(file=buf) |
| 58 | return buf.getvalue() |
| 59 | |
| 60 | |
| 61 | def _note(pitch: int, velocity: int = 80, start: int = 0, duration: int = 480) -> NoteKey: |
| 62 | return NoteKey( |
| 63 | pitch=pitch, velocity=velocity, start_tick=start, |
| 64 | duration_ticks=duration, channel=0, |
| 65 | ) |
| 66 | |
| 67 | |
| 68 | # --------------------------------------------------------------------------- |
| 69 | # extract_notes |
| 70 | # --------------------------------------------------------------------------- |
| 71 | |
| 72 | class TestExtractNotes: |
| 73 | def test_empty_midi_returns_no_notes(self) -> None: |
| 74 | midi_bytes = _build_midi([]) |
| 75 | notes, tpb = extract_notes(midi_bytes) |
| 76 | assert notes == [] |
| 77 | assert tpb == 480 |
| 78 | |
| 79 | def test_single_note_extracted(self) -> None: |
| 80 | midi_bytes = _build_midi([(60, 80, 0, 480)]) # C4 |
| 81 | notes, tpb = extract_notes(midi_bytes) |
| 82 | assert len(notes) == 1 |
| 83 | assert notes[0]["pitch"] == 60 |
| 84 | assert notes[0]["velocity"] == 80 |
| 85 | assert notes[0]["start_tick"] == 0 |
| 86 | assert notes[0]["duration_ticks"] == 480 |
| 87 | |
| 88 | def test_multiple_notes_extracted(self) -> None: |
| 89 | midi_bytes = _build_midi([ |
| 90 | (60, 80, 0, 480), |
| 91 | (64, 90, 480, 480), |
| 92 | (67, 70, 960, 480), |
| 93 | ]) |
| 94 | notes, _ = extract_notes(midi_bytes) |
| 95 | assert len(notes) == 3 |
| 96 | |
| 97 | def test_notes_sorted_by_start_tick(self) -> None: |
| 98 | midi_bytes = _build_midi([ |
| 99 | (67, 70, 960, 240), |
| 100 | (60, 80, 0, 480), |
| 101 | (64, 90, 480, 480), |
| 102 | ]) |
| 103 | notes, _ = extract_notes(midi_bytes) |
| 104 | ticks = [n["start_tick"] for n in notes] |
| 105 | assert ticks == sorted(ticks) |
| 106 | |
| 107 | def test_invalid_bytes_raises_value_error(self) -> None: |
| 108 | with pytest.raises(ValueError): |
| 109 | extract_notes(b"not a midi file") |
| 110 | |
| 111 | def test_ticks_per_beat_is_returned(self) -> None: |
| 112 | midi_bytes = _build_midi([(60, 80, 0, 480)]) |
| 113 | _, tpb = extract_notes(midi_bytes) |
| 114 | assert tpb == 480 |
| 115 | |
| 116 | |
| 117 | # --------------------------------------------------------------------------- |
| 118 | # lcs_edit_script |
| 119 | # --------------------------------------------------------------------------- |
| 120 | |
| 121 | class TestLCSEditScript: |
| 122 | """LCS tests use start_tick=pitch so same-pitch notes always compare equal. |
| 123 | |
| 124 | NoteKey equality requires ALL five fields to match. Using start_tick=pitch |
| 125 | ensures that notes with the same pitch in base and target are considered |
| 126 | identical by LCS, giving intuitive edit scripts. |
| 127 | """ |
| 128 | |
| 129 | def _nk(self, pitch: int) -> NoteKey: |
| 130 | """Make a NoteKey where start_tick equals pitch for stable matching.""" |
| 131 | return NoteKey( |
| 132 | pitch=pitch, velocity=80, |
| 133 | start_tick=pitch, # deterministic: same pitch → same tick → same key |
| 134 | duration_ticks=480, channel=0, |
| 135 | ) |
| 136 | |
| 137 | def _seq(self, pitches: list[int]) -> list[NoteKey]: |
| 138 | return [self._nk(p) for p in pitches] |
| 139 | |
| 140 | def test_identical_sequences_keeps_all(self) -> None: |
| 141 | notes = self._seq([60, 62, 64]) |
| 142 | steps = lcs_edit_script(notes, notes) |
| 143 | kinds = [s.kind for s in steps] |
| 144 | assert kinds == ["keep", "keep", "keep"] |
| 145 | |
| 146 | def test_empty_to_sequence_all_inserts(self) -> None: |
| 147 | target = self._seq([60, 62]) |
| 148 | steps = lcs_edit_script([], target) |
| 149 | assert all(s.kind == "insert" for s in steps) |
| 150 | assert len(steps) == 2 |
| 151 | |
| 152 | def test_sequence_to_empty_all_deletes(self) -> None: |
| 153 | base = self._seq([60, 62]) |
| 154 | steps = lcs_edit_script(base, []) |
| 155 | assert all(s.kind == "delete" for s in steps) |
| 156 | assert len(steps) == 2 |
| 157 | |
| 158 | def test_single_insert_at_end(self) -> None: |
| 159 | # base=[60,62], target=[60,62,64] → keep 60, keep 62, insert 64 |
| 160 | base = self._seq([60, 62]) |
| 161 | target = self._seq([60, 62, 64]) |
| 162 | steps = lcs_edit_script(base, target) |
| 163 | keeps = [s for s in steps if s.kind == "keep"] |
| 164 | inserts = [s for s in steps if s.kind == "insert"] |
| 165 | assert len(keeps) == 2 |
| 166 | assert len(inserts) == 1 |
| 167 | assert inserts[0].note["pitch"] == 64 |
| 168 | |
| 169 | def test_single_delete_from_middle(self) -> None: |
| 170 | # base=[60,62,64], target=[60,64] → keep 60, delete 62, keep 64 |
| 171 | # NoteKeys with start_tick=pitch ensure 64@64 matches 64@64. |
| 172 | base = self._seq([60, 62, 64]) |
| 173 | target = self._seq([60, 64]) |
| 174 | steps = lcs_edit_script(base, target) |
| 175 | deletes = [s for s in steps if s.kind == "delete"] |
| 176 | assert len(deletes) == 1 |
| 177 | assert deletes[0].note["pitch"] == 62 |
| 178 | |
| 179 | def test_pitch_change_is_delete_plus_insert(self) -> None: |
| 180 | # A note with a different pitch → one delete + one insert. |
| 181 | base = [_note(60)] |
| 182 | target = [_note(62)] |
| 183 | steps = lcs_edit_script(base, target) |
| 184 | kinds = {s.kind for s in steps} |
| 185 | assert "delete" in kinds |
| 186 | assert "insert" in kinds |
| 187 | assert "keep" not in kinds |
| 188 | |
| 189 | def test_lcs_is_minimal_keeps_equal_lcs_length(self) -> None: |
| 190 | # LCS of [60,62,64,65] and [60,64,65,67] is [60,64,65] (length 3) |
| 191 | # because 60@60, 64@64, 65@65 all have matching counterparts in target. |
| 192 | base = self._seq([60, 62, 64, 65]) |
| 193 | target = self._seq([60, 64, 65, 67]) |
| 194 | steps = lcs_edit_script(base, target) |
| 195 | keeps = [s for s in steps if s.kind == "keep"] |
| 196 | assert len(keeps) == 3 |
| 197 | |
| 198 | def test_empty_both_returns_empty(self) -> None: |
| 199 | steps = lcs_edit_script([], []) |
| 200 | assert steps == [] |
| 201 | |
| 202 | def test_step_indices_are_consistent(self) -> None: |
| 203 | base = self._seq([60, 62, 64]) |
| 204 | target = self._seq([60, 64]) |
| 205 | steps = lcs_edit_script(base, target) |
| 206 | base_indices = [s.base_index for s in steps if s.kind != "insert"] |
| 207 | target_indices = [s.target_index for s in steps if s.kind != "delete"] |
| 208 | assert base_indices == sorted(base_indices) |
| 209 | assert target_indices == sorted(target_indices) |
| 210 | |
| 211 | def test_reorder_detected_as_delete_insert(self) -> None: |
| 212 | # Swapping pitches at the same positions → notes differ → no keeps. |
| 213 | # Using start_tick=0 for all to guarantee tick collision is NOT the issue; |
| 214 | # the pitch mismatch is what creates the delete+insert. |
| 215 | base = [NoteKey(pitch=60, velocity=80, start_tick=0, duration_ticks=480, channel=0), |
| 216 | NoteKey(pitch=62, velocity=80, start_tick=480, duration_ticks=480, channel=0)] |
| 217 | target = [NoteKey(pitch=62, velocity=80, start_tick=0, duration_ticks=480, channel=0), |
| 218 | NoteKey(pitch=60, velocity=80, start_tick=480, duration_ticks=480, channel=0)] |
| 219 | steps = lcs_edit_script(base, target) |
| 220 | keeps = [s for s in steps if s.kind == "keep"] |
| 221 | # No notes match exactly (same pitch at same tick is not present in both). |
| 222 | assert len(keeps) == 0 |
| 223 | |
| 224 | |
| 225 | # --------------------------------------------------------------------------- |
| 226 | # diff_midi_notes |
| 227 | # --------------------------------------------------------------------------- |
| 228 | |
| 229 | class TestDiffMidiNotes: |
| 230 | def test_no_change_returns_empty_ops(self) -> None: |
| 231 | midi_bytes = _build_midi([(60, 80, 0, 480)]) |
| 232 | delta = diff_midi_notes(midi_bytes, midi_bytes) |
| 233 | assert delta["ops"] == [] |
| 234 | |
| 235 | def test_no_change_summary(self) -> None: |
| 236 | midi_bytes = _build_midi([(60, 80, 0, 480)]) |
| 237 | delta = diff_midi_notes(midi_bytes, midi_bytes) |
| 238 | assert "no note changes" in delta["summary"] |
| 239 | |
| 240 | def test_add_note_returns_insert_op(self) -> None: |
| 241 | base_bytes = _build_midi([(60, 80, 0, 480)]) |
| 242 | target_bytes = _build_midi([(60, 80, 0, 480), (64, 80, 480, 480)]) |
| 243 | delta = diff_midi_notes(base_bytes, target_bytes) |
| 244 | inserts = [op for op in delta["ops"] if op["op"] == "insert"] |
| 245 | assert len(inserts) == 1 |
| 246 | |
| 247 | def test_remove_note_returns_delete_op(self) -> None: |
| 248 | base_bytes = _build_midi([(60, 80, 0, 480), (64, 80, 480, 480)]) |
| 249 | target_bytes = _build_midi([(60, 80, 0, 480)]) |
| 250 | delta = diff_midi_notes(base_bytes, target_bytes) |
| 251 | deletes = [op for op in delta["ops"] if op["op"] == "delete"] |
| 252 | assert len(deletes) == 1 |
| 253 | |
| 254 | def test_change_pitch_produces_delete_and_insert(self) -> None: |
| 255 | base_bytes = _build_midi([(60, 80, 0, 480)]) |
| 256 | target_bytes = _build_midi([(62, 80, 0, 480)]) |
| 257 | delta = diff_midi_notes(base_bytes, target_bytes) |
| 258 | kinds = {op["op"] for op in delta["ops"]} |
| 259 | assert "delete" in kinds |
| 260 | assert "insert" in kinds |
| 261 | |
| 262 | def test_summary_mentions_added_notes(self) -> None: |
| 263 | base_bytes = _build_midi([(60, 80, 0, 480)]) |
| 264 | target_bytes = _build_midi([(60, 80, 0, 480), (64, 80, 480, 480)]) |
| 265 | delta = diff_midi_notes(base_bytes, target_bytes) |
| 266 | assert "added" in delta["summary"] |
| 267 | |
| 268 | def test_summary_mentions_removed_notes(self) -> None: |
| 269 | base_bytes = _build_midi([(60, 80, 0, 480), (64, 80, 480, 480)]) |
| 270 | target_bytes = _build_midi([(60, 80, 0, 480)]) |
| 271 | delta = diff_midi_notes(base_bytes, target_bytes) |
| 272 | assert "removed" in delta["summary"] |
| 273 | |
| 274 | def test_summary_singular_for_one_note(self) -> None: |
| 275 | base_bytes = _build_midi([]) |
| 276 | target_bytes = _build_midi([(60, 80, 0, 480)]) |
| 277 | delta = diff_midi_notes(base_bytes, target_bytes) |
| 278 | assert "1 note added" in delta["summary"] |
| 279 | |
| 280 | def test_summary_plural_for_multiple_notes(self) -> None: |
| 281 | base_bytes = _build_midi([]) |
| 282 | target_bytes = _build_midi([(60, 80, 0, 480), (64, 80, 480, 480)]) |
| 283 | delta = diff_midi_notes(base_bytes, target_bytes) |
| 284 | assert "2 notes added" in delta["summary"] |
| 285 | |
| 286 | def test_content_id_is_deterministic(self) -> None: |
| 287 | midi_bytes = _build_midi([(60, 80, 0, 480)]) |
| 288 | empty_bytes = _build_midi([]) |
| 289 | delta1 = diff_midi_notes(empty_bytes, midi_bytes) |
| 290 | delta2 = diff_midi_notes(empty_bytes, midi_bytes) |
| 291 | ids1 = [op["content_id"] for op in delta1["ops"]] |
| 292 | ids2 = [op["content_id"] for op in delta2["ops"]] |
| 293 | assert ids1 == ids2 |
| 294 | |
| 295 | def test_content_ids_differ_for_different_notes(self) -> None: |
| 296 | empty_bytes = _build_midi([]) |
| 297 | midi_c4 = _build_midi([(60, 80, 0, 480)]) |
| 298 | midi_d4 = _build_midi([(62, 80, 0, 480)]) |
| 299 | delta_c4 = diff_midi_notes(empty_bytes, midi_c4) |
| 300 | delta_d4 = diff_midi_notes(empty_bytes, midi_d4) |
| 301 | id_c4 = delta_c4["ops"][0]["content_id"] |
| 302 | id_d4 = delta_d4["ops"][0]["content_id"] |
| 303 | assert id_c4 != id_d4 |
| 304 | |
| 305 | def test_content_summary_is_human_readable(self) -> None: |
| 306 | empty_bytes = _build_midi([]) |
| 307 | target_bytes = _build_midi([(60, 80, 0, 480)]) # C4 |
| 308 | delta = diff_midi_notes(empty_bytes, target_bytes) |
| 309 | summary = delta["ops"][0]["content_summary"] |
| 310 | assert "C4" in summary |
| 311 | assert "vel=80" in summary |
| 312 | |
| 313 | def test_domain_is_midi_notes(self) -> None: |
| 314 | midi_bytes = _build_midi([(60, 80, 0, 480)]) |
| 315 | empty_bytes = _build_midi([]) |
| 316 | delta = diff_midi_notes(empty_bytes, midi_bytes) |
| 317 | assert delta["domain"] == "midi_notes" |
| 318 | |
| 319 | def test_invalid_base_raises_value_error(self) -> None: |
| 320 | valid = _build_midi([(60, 80, 0, 480)]) |
| 321 | with pytest.raises(ValueError): |
| 322 | diff_midi_notes(b"garbage", valid) |
| 323 | |
| 324 | def test_invalid_target_raises_value_error(self) -> None: |
| 325 | valid = _build_midi([(60, 80, 0, 480)]) |
| 326 | with pytest.raises(ValueError): |
| 327 | diff_midi_notes(valid, b"garbage") |
| 328 | |
| 329 | def test_file_path_appears_in_content_summary_context(self) -> None: |
| 330 | # file_path is used only for logging; no crash expected. |
| 331 | base_bytes = _build_midi([]) |
| 332 | target_bytes = _build_midi([(60, 80, 0, 480)]) |
| 333 | delta = diff_midi_notes( |
| 334 | base_bytes, target_bytes, file_path="tracks/piano.mid" |
| 335 | ) |
| 336 | assert len(delta["ops"]) == 1 |
| 337 | |
| 338 | def test_position_reflects_sequence_index(self) -> None: |
| 339 | empty = _build_midi([]) |
| 340 | two_notes = _build_midi([(60, 80, 0, 480), (64, 80, 480, 480)]) |
| 341 | delta = diff_midi_notes(empty, two_notes) |
| 342 | positions = [op["position"] for op in delta["ops"]] |
| 343 | assert 0 in positions |
| 344 | assert 1 in positions |