feat: add Vitest unit testing infrastructure with initial test suite.

src/test/utils/mock-data.ts

@@ -0,0 +1,155 @@
+import { KGMidiNote } from '../../core/midi/KGMidiNote'
+import { KGProject } from '../../core/KGProject'
+import { KGMidiTrack } from '../../core/track/KGMidiTrack'
+import { KGMidiRegion } from '../../core/region/KGMidiRegion'
+
+/**
+ * Test data factories for creating mock objects
+ * These help create consistent test data across different test files
+ */
+
+export const createMockMidiNote = (overrides: Partial<{
+  pitch: number
+  velocity: number
+  startBeat: number
+  endBeat: number
+  id: string
+}> = {}): KGMidiNote => {
+  const defaults = {
+    id: 'test-note-1',
+    startBeat: 0,
+    endBeat: 1,
+    pitch: 60, // Middle C
+    velocity: 80,
+    ...overrides
+  }
+  
+  return new KGMidiNote(
+    defaults.id,
+    defaults.startBeat,
+    defaults.endBeat,
+    defaults.pitch,
+    defaults.velocity
+  )
+}
+
+export const createMockMidiRegion = (overrides: Partial<{
+  id: string
+  trackId: string
+  trackIndex: number
+  name: string
+  startFromBeat: number
+  length: number
+  notes: KGMidiNote[]
+}> = {}): KGMidiRegion => {
+  const defaults = {
+    id: 'test-region-1',
+    trackId: 'test-track-1',
+    trackIndex: 0,
+    name: 'Test Region',
+    startFromBeat: 0,
+    length: 4,
+    ...overrides
+  }
+  
+  const region = new KGMidiRegion(
+    defaults.id,
+    defaults.trackId,
+    defaults.trackIndex,
+    defaults.name,
+    defaults.startFromBeat,
+    defaults.length
+  )
+  
+  // Add notes if provided
+  if (overrides.notes) {
+    overrides.notes.forEach(note => region.addNote(note))
+  }
+  
+  return region
+}
+
+export const createMockMidiTrack = (overrides: Partial<{
+  name: string
+  id: number
+  instrument: string
+  volume: number
+  regions: KGMidiRegion[]
+}> = {}): KGMidiTrack => {
+  const defaults = {
+    name: 'Test Track',
+    id: 0,
+    instrument: 'acoustic_grand_piano' as const,
+    volume: 0.8,
+    ...overrides
+  }
+  
+  const track = new KGMidiTrack(
+    defaults.name,
+    defaults.id,
+    defaults.instrument as keyof typeof import('../../constants/generalMidiConstants').FLUIDR3_INSTRUMENT_MAP,
+    defaults.volume
+  )
+  
+  // Add regions if provided
+  if (overrides.regions) {
+    track.setRegions(overrides.regions)
+  }
+  
+  return track
+}
+
+export const createMockProject = (overrides: Partial<{
+  name: string
+  bpm: number
+  timeSignature: { numerator: number; denominator: number }
+  tracks: KGMidiTrack[]
+}> = {}): KGProject => {
+  const defaults = {
+    name: 'Test Project',
+    bpm: 120,
+    timeSignature: { numerator: 4, denominator: 4 },
+    tracks: [],
+    ...overrides
+  }
+  
+  const project = new KGProject(
+    defaults.name,
+    32, // maxBars
+    0,  // currentBars
+    defaults.bpm,
+    defaults.timeSignature,
+    'C major', // keySignature
+    defaults.tracks, // tracks
+    1 // projectStructureVersion
+  )
+  
+  return project
+}
+
+// Common test scenarios
+export const createBasicProjectWithTrack = (): { project: KGProject; track: KGMidiTrack; region: KGMidiRegion } => {
+  const notes = [
+    createMockMidiNote({ pitch: 60, startBeat: 0, endBeat: 1 }),
+    createMockMidiNote({ pitch: 64, startBeat: 1, endBeat: 2 }),
+  ]
+  
+  const region = createMockMidiRegion({ 
+    id: 'region-1',
+    trackId: 'track-1',
+    notes 
+  })
+  
+  const track = createMockMidiTrack({ 
+    id: 1,
+    name: 'Track 1',
+    regions: [region] 
+  })
+  
+  const project = createMockProject({ 
+    name: 'Basic Test Project',
+    tracks: [track] 
+  })
+  
+  return { project, track, region }
+}