feat: added merge MIDI regions feature

src/core/commands/region/MergeMidiRegionsCommand.test.ts

@@ -0,0 +1,166 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { KGCore } from '../../KGCore';
+import { MergeMidiRegionsCommand } from './MergeMidiRegionsCommand';
+import { createMockMidiNote, createMockMidiRegion, createMockMidiTrack, createMockProject } from '../../../test/utils/mock-data';
+
+const storeState = {
+  showPianoRoll: false,
+  activeRegionId: null as string | null,
+  setShowPianoRoll: vi.fn(),
+  setActiveRegionId: vi.fn(),
+};
+
+vi.mock('../../KGCore', () => ({
+  KGCore: {
+    instance: vi.fn(),
+  }
+}));
+
+vi.mock('../../../stores/projectStore', () => ({
+  useProjectStore: {
+    getState: vi.fn(() => storeState),
+  }
+}));
+
+interface MockCore {
+  getCurrentProject: ReturnType<typeof vi.fn>;
+  getSelectedItems: ReturnType<typeof vi.fn>;
+  clearSelectedItems: ReturnType<typeof vi.fn>;
+  addSelectedItem: ReturnType<typeof vi.fn>;
+  addSelectedItems: ReturnType<typeof vi.fn>;
+}
+
+describe('MergeMidiRegionsCommand', () => {
+  let mockCore: MockCore;
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+    storeState.showPianoRoll = false;
+    storeState.activeRegionId = null;
+
+    mockCore = {
+      getCurrentProject: vi.fn(),
+      getSelectedItems: vi.fn().mockReturnValue([]),
+      clearSelectedItems: vi.fn(),
+      addSelectedItem: vi.fn(),
+      addSelectedItems: vi.fn(),
+    };
+
+    vi.mocked(KGCore.instance).mockReturnValue(mockCore as unknown as KGCore);
+  });
+
+  it('merges multiple MIDI regions and preserves absolute note timing', () => {
+    const regionA = createMockMidiRegion({
+      id: 'region-a',
+      trackId: '1',
+      trackIndex: 0,
+      startFromBeat: 4,
+      length: 2,
+      notes: [createMockMidiNote({ id: 'note-a', startBeat: 0.5, endBeat: 1.5, pitch: 60 })],
+    });
+    const regionB = createMockMidiRegion({
+      id: 'region-b',
+      trackId: '1',
+      trackIndex: 0,
+      startFromBeat: 8,
+      length: 4,
+      notes: [createMockMidiNote({ id: 'note-b', startBeat: 1, endBeat: 2, pitch: 67 })],
+    });
+    const regionC = createMockMidiRegion({
+      id: 'region-c',
+      trackId: '1',
+      trackIndex: 0,
+      startFromBeat: 14,
+      length: 2,
+      notes: [createMockMidiNote({ id: 'note-c', startBeat: 0, endBeat: 1, pitch: 72 })],
+    });
+    const track = createMockMidiTrack({ id: 1, regions: [regionA, regionB, regionC] });
+    track.setTrackIndex(0);
+    mockCore.getCurrentProject.mockReturnValue(createMockProject({ tracks: [track] }));
+
+    const command = new MergeMidiRegionsCommand(['region-b', 'region-a', 'region-c']);
+
+    command.execute();
+
+    expect(track.getRegions()).toEqual([regionA]);
+    expect(regionA.getStartFromBeat()).toBe(4);
+    expect(regionA.getLength()).toBe(12);
+
+    const mergedNotes = regionA.getNotes();
+    expect(mergedNotes).toHaveLength(3);
+    expect(mergedNotes.map(note => [note.getId(), note.getStartBeat(), note.getEndBeat()])).toEqual([
+      ['note-a', 0.5, 1.5],
+      ['note-b', 5, 6],
+      ['note-c', 10, 11],
+    ]);
+    expect(mockCore.clearSelectedItems).toHaveBeenCalledTimes(1);
+    expect(mockCore.addSelectedItem).toHaveBeenCalledWith(regionA);
+  });
+
+  it('retargets the piano roll to the surviving region when the active region is removed', () => {
+    const regionA = createMockMidiRegion({ id: 'region-a', trackId: '1', trackIndex: 0, startFromBeat: 0, length: 4 });
+    const regionB = createMockMidiRegion({ id: 'region-b', trackId: '1', trackIndex: 0, startFromBeat: 6, length: 4 });
+    const track = createMockMidiTrack({ id: 1, regions: [regionA, regionB] });
+    track.setTrackIndex(0);
+    mockCore.getCurrentProject.mockReturnValue(createMockProject({ tracks: [track] }));
+    storeState.showPianoRoll = true;
+    storeState.activeRegionId = 'region-b';
+
+    const command = new MergeMidiRegionsCommand(['region-a', 'region-b']);
+
+    command.execute();
+
+    expect(storeState.setActiveRegionId).toHaveBeenCalledWith('region-a');
+    expect(storeState.setShowPianoRoll).toHaveBeenCalledWith(true);
+  });
+
+  it('undo restores original regions, notes, selection, and piano roll state', () => {
+    const regionA = createMockMidiRegion({
+      id: 'region-a',
+      trackId: '1',
+      trackIndex: 0,
+      startFromBeat: 4,
+      length: 4,
+      notes: [createMockMidiNote({ id: 'note-a', startBeat: 0, endBeat: 1 })],
+    });
+    const regionB = createMockMidiRegion({
+      id: 'region-b',
+      trackId: '1',
+      trackIndex: 0,
+      startFromBeat: 10,
+      length: 2,
+      notes: [createMockMidiNote({ id: 'note-b', startBeat: 0.5, endBeat: 1.5 })],
+    });
+    const otherRegion = createMockMidiRegion({
+      id: 'region-x',
+      trackId: '1',
+      trackIndex: 0,
+      startFromBeat: 20,
+      length: 2,
+    });
+    const track = createMockMidiTrack({ id: 1, regions: [regionA, regionB, otherRegion] });
+    track.setTrackIndex(0);
+    mockCore.getCurrentProject.mockReturnValue(createMockProject({ tracks: [track] }));
+    mockCore.getSelectedItems.mockReturnValue([regionA, regionB]);
+    storeState.showPianoRoll = true;
+    storeState.activeRegionId = 'region-b';
+
+    const command = new MergeMidiRegionsCommand(['region-a', 'region-b']);
+
+    command.execute();
+    command.undo();
+
+    expect(track.getRegions()).toEqual([regionA, regionB, otherRegion]);
+    expect(regionA.getLength()).toBe(4);
+    expect(regionA.getNotes().map(note => [note.getId(), note.getStartBeat(), note.getEndBeat()])).toEqual([
+      ['note-a', 0, 1],
+    ]);
+    expect(regionB.getLength()).toBe(2);
+    expect(regionB.getNotes().map(note => [note.getId(), note.getStartBeat(), note.getEndBeat()])).toEqual([
+      ['note-b', 0.5, 1.5],
+    ]);
+    expect(mockCore.addSelectedItems).toHaveBeenCalledWith([regionA, regionB]);
+    expect(storeState.setShowPianoRoll).toHaveBeenCalledWith(true);
+    expect(storeState.setActiveRegionId).toHaveBeenLastCalledWith('region-b');
+  });
+});