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

src/test/mocks/tone.ts

@@ -0,0 +1,115 @@
+import { vi } from 'vitest'
+
+/**
+ * Mock implementation of Tone.js for testing
+ * This provides consistent, deterministic behavior for audio-related tests
+ */
+
+// Mock Sampler class
+export const MockSampler = vi.fn().mockImplementation(() => ({
+  triggerAttackRelease: vi.fn(),
+  triggerAttack: vi.fn(),
+  triggerRelease: vi.fn(),
+  dispose: vi.fn(),
+  loaded: true,
+  volume: {
+    value: -12
+  },
+  connect: vi.fn(),
+  disconnect: vi.fn(),
+  toDestination: vi.fn()
+}))
+
+// Mock Transport object
+export const MockTransport = {
+  start: vi.fn(),
+  stop: vi.fn(),
+  pause: vi.fn(),
+  position: '0:0:0',
+  bpm: {
+    value: 120,
+    rampTo: vi.fn()
+  },
+  timeSignature: [4, 4],
+  state: 'stopped',
+  scheduleOnce: vi.fn(),
+  scheduleRepeat: vi.fn(),
+  cancel: vi.fn(),
+  clear: vi.fn()
+}
+
+// Mock Destination
+export const MockDestination = {
+  volume: {
+    value: -12
+  },
+  mute: false,
+  connect: vi.fn(),
+  disconnect: vi.fn()
+}
+
+// Mock ToneAudioBuffer
+export const MockToneAudioBuffer = vi.fn().mockImplementation(() => ({
+  loaded: true,
+  dispose: vi.fn(),
+  get: vi.fn(),
+  set: vi.fn(),
+  load: vi.fn().mockResolvedValue(undefined)
+}))
+
+// Mock Gain node
+export const MockGain = vi.fn().mockImplementation(() => ({
+  gain: {
+    value: 1,
+    setValueAtTime: vi.fn(),
+    linearRampToValueAtTime: vi.fn(),
+    exponentialRampToValueAtTime: vi.fn()
+  },
+  connect: vi.fn(),
+  disconnect: vi.fn(),
+  dispose: vi.fn()
+}))
+
+// Mock Meter
+export const MockMeter = vi.fn().mockImplementation(() => ({
+  getValue: vi.fn().mockReturnValue(-Infinity),
+  connect: vi.fn(),
+  disconnect: vi.fn(),
+  dispose: vi.fn()
+}))
+
+// Complete Tone.js mock
+export const ToneMock = {
+  Sampler: MockSampler,
+  Transport: MockTransport,
+  Destination: MockDestination,
+  ToneAudioBuffer: MockToneAudioBuffer,
+  Gain: MockGain,
+  Meter: MockMeter,
+  
+  // Context management
+  start: vi.fn().mockResolvedValue(undefined),
+  getContext: vi.fn().mockReturnValue({
+    state: 'running',
+    resume: vi.fn().mockResolvedValue(undefined),
+    suspend: vi.fn().mockResolvedValue(undefined),
+    close: vi.fn().mockResolvedValue(undefined)
+  }),
+  
+  // Time utilities
+  Time: vi.fn().mockImplementation((time) => ({
+    toSeconds: vi.fn().mockReturnValue(parseFloat(time) || 0),
+    valueOf: vi.fn().mockReturnValue(parseFloat(time) || 0)
+  })),
+  
+  // Frequency utilities
+  Frequency: vi.fn().mockImplementation((freq) => ({
+    toFrequency: vi.fn().mockReturnValue(parseFloat(freq) || 440),
+    valueOf: vi.fn().mockReturnValue(parseFloat(freq) || 440)
+  }))
+}
+
+// Setup the global mock
+export const setupToneMocks = () => {
+  vi.doMock('tone', () => ToneMock)
+}