test: add unit tests for ChangeTracker lifecycle methods

Cover captureCanvasState guards (no graph, changeCount, isLoadingGraph,
_restoringState, inactive tracker), state capture with undo queue
management, deactivate (active + inactive paths), prepareForSave
(active + inactive paths), and deprecated checkState wrapper.

src/scripts/changeTracker.test.ts

@@ -0,0 +1,271 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+import type { ComfyWorkflowJSON } from '@/platform/workflow/validation/schemas/workflowSchema'
+
+const mockNodeOutputStore = vi.hoisted(() => ({
+  snapshotOutputs: vi.fn(() => ({})),
+  restoreOutputs: vi.fn()
+}))
+
+const mockSubgraphNavigationStore = vi.hoisted(() => ({
+  exportState: vi.fn(() => []),
+  restoreState: vi.fn()
+}))
+
+const mockWorkflowStore = vi.hoisted(() => ({
+  activeWorkflow: null as { changeTracker: unknown } | null,
+  getWorkflowByPath: vi.fn()
+}))
+
+vi.mock('@/scripts/app', () => ({
+  app: {
+    graph: {},
+    rootGraph: {
+      serialize: vi.fn(() => ({
+        nodes: [],
+        links: [],
+        groups: [],
+        extra: {},
+        config: {},
+        version: 0.4,
+        last_node_id: 0,
+        last_link_id: 0
+      }))
+    },
+    canvas: {
+      ds: { scale: 1, offset: [0, 0] }
+    }
+  }
+}))
+
+vi.mock('@/scripts/api', () => ({
+  api: {
+    dispatchCustomEvent: vi.fn(),
+    addEventListener: vi.fn(),
+    removeEventListener: vi.fn()
+  }
+}))
+
+vi.mock('@/stores/nodeOutputStore', () => ({
+  useNodeOutputStore: vi.fn(() => mockNodeOutputStore)
+}))
+
+vi.mock('@/stores/subgraphNavigationStore', () => ({
+  useSubgraphNavigationStore: vi.fn(() => mockSubgraphNavigationStore)
+}))
+
+vi.mock('@/platform/workflow/management/stores/workflowStore', () => ({
+  ComfyWorkflow: class {},
+  useWorkflowStore: vi.fn(() => mockWorkflowStore)
+}))
+
+import { app } from '@/scripts/app'
+import { ChangeTracker } from '@/scripts/changeTracker'
+
+let nodeIdCounter = 0
+
+function createState(nodeCount = 0): ComfyWorkflowJSON {
+  const nodes = Array.from({ length: nodeCount }, () => ({
+    id: ++nodeIdCounter,
+    type: 'TestNode',
+    pos: [0, 0],
+    size: [100, 50],
+    flags: {},
+    order: 0,
+    inputs: [],
+    outputs: [],
+    properties: {}
+  }))
+  return {
+    nodes,
+    links: [],
+    groups: [],
+    extra: {},
+    config: {},
+    version: 0.4,
+    last_node_id: nodeIdCounter,
+    last_link_id: 0
+  } as unknown as ComfyWorkflowJSON
+}
+
+function createTracker(initialState?: ComfyWorkflowJSON): ChangeTracker {
+  const state = initialState ?? createState()
+  const workflow = { path: '/test/workflow.json' } as never
+  const tracker = new ChangeTracker(workflow, state)
+  mockWorkflowStore.activeWorkflow = { changeTracker: tracker }
+  return tracker
+}
+
+function mockCanvasState(state: ComfyWorkflowJSON) {
+  vi.mocked(app.rootGraph.serialize).mockReturnValue(state as never)
+}
+
+describe('ChangeTracker', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+    nodeIdCounter = 0
+    ChangeTracker.isLoadingGraph = false
+    mockWorkflowStore.activeWorkflow = null
+    mockWorkflowStore.getWorkflowByPath.mockReturnValue(null)
+  })
+
+  describe('captureCanvasState', () => {
+    describe('guards', () => {
+      it('is a no-op when app.graph is falsy', () => {
+        const tracker = createTracker()
+        const original = tracker.activeState
+
+        const savedGraph = app.graph
+        ;(app as { graph: unknown }).graph = null
+        tracker.captureCanvasState()
+        ;(app as { graph: unknown }).graph = savedGraph
+
+        expect(app.rootGraph.serialize).not.toHaveBeenCalled()
+        expect(tracker.activeState).toBe(original)
+      })
+
+      it('is a no-op when changeCount > 0', () => {
+        const tracker = createTracker()
+        tracker.beforeChange()
+
+        tracker.captureCanvasState()
+
+        expect(app.rootGraph.serialize).not.toHaveBeenCalled()
+      })
+
+      it('is a no-op when isLoadingGraph is true', () => {
+        const tracker = createTracker()
+        ChangeTracker.isLoadingGraph = true
+
+        tracker.captureCanvasState()
+
+        expect(app.rootGraph.serialize).not.toHaveBeenCalled()
+      })
+
+      it('is a no-op when _restoringState is true', () => {
+        const tracker = createTracker()
+        tracker._restoringState = true
+
+        tracker.captureCanvasState()
+
+        expect(app.rootGraph.serialize).not.toHaveBeenCalled()
+      })
+
+      it('is a no-op and logs error when called on inactive tracker', () => {
+        const tracker = createTracker()
+        mockWorkflowStore.activeWorkflow = { changeTracker: {} }
+
+        tracker.captureCanvasState()
+
+        expect(app.rootGraph.serialize).not.toHaveBeenCalled()
+      })
+    })
+
+    describe('state capture', () => {
+      it('pushes to undoQueue and updates activeState when state differs', () => {
+        const initial = createState(1)
+        const tracker = createTracker(initial)
+        const changed = createState(2)
+        mockCanvasState(changed)
+
+        tracker.captureCanvasState()
+
+        expect(tracker.undoQueue).toHaveLength(1)
+        expect(tracker.undoQueue[0]).toEqual(initial)
+        expect(tracker.activeState).toEqual(changed)
+      })
+
+      it('does not push when state is identical', () => {
+        const state = createState()
+        const tracker = createTracker(state)
+        mockCanvasState(state)
+
+        tracker.captureCanvasState()
+
+        expect(tracker.undoQueue).toHaveLength(0)
+      })
+
+      it('clears redoQueue on new change', () => {
+        const tracker = createTracker(createState(1))
+        tracker.redoQueue.push(createState(3))
+        mockCanvasState(createState(2))
+
+        tracker.captureCanvasState()
+
+        expect(tracker.redoQueue).toHaveLength(0)
+      })
+
+      it('caps undoQueue at MAX_HISTORY', () => {
+        const tracker = createTracker(createState(1))
+        for (let i = 0; i < ChangeTracker.MAX_HISTORY; i++) {
+          tracker.undoQueue.push(createState(1))
+        }
+        expect(tracker.undoQueue).toHaveLength(ChangeTracker.MAX_HISTORY)
+
+        mockCanvasState(createState(2))
+        tracker.captureCanvasState()
+
+        expect(tracker.undoQueue).toHaveLength(ChangeTracker.MAX_HISTORY)
+      })
+    })
+  })
+
+  describe('deactivate', () => {
+    it('captures canvas state then stores viewport/outputs', () => {
+      const tracker = createTracker(createState(1))
+      const changed = createState(2)
+      mockCanvasState(changed)
+
+      tracker.deactivate()
+
+      expect(tracker.activeState).toEqual(changed)
+      expect(mockNodeOutputStore.snapshotOutputs).toHaveBeenCalled()
+      expect(mockSubgraphNavigationStore.exportState).toHaveBeenCalled()
+    })
+
+    it('still stores viewport when captureCanvasState is no-op (inactive)', () => {
+      const tracker = createTracker()
+      mockWorkflowStore.activeWorkflow = { changeTracker: {} }
+
+      tracker.deactivate()
+
+      expect(app.rootGraph.serialize).not.toHaveBeenCalled()
+      expect(mockNodeOutputStore.snapshotOutputs).toHaveBeenCalled()
+    })
+  })
+
+  describe('prepareForSave', () => {
+    it('captures canvas state when tracker is active', () => {
+      const tracker = createTracker(createState(1))
+      const changed = createState(2)
+      mockCanvasState(changed)
+
+      tracker.prepareForSave()
+
+      expect(tracker.activeState).toEqual(changed)
+    })
+
+    it('is a no-op when tracker is inactive', () => {
+      const tracker = createTracker()
+      const original = tracker.activeState
+      mockWorkflowStore.activeWorkflow = { changeTracker: {} }
+
+      tracker.prepareForSave()
+
+      expect(app.rootGraph.serialize).not.toHaveBeenCalled()
+      expect(tracker.activeState).toBe(original)
+    })
+  })
+
+  describe('checkState (deprecated)', () => {
+    it('delegates to captureCanvasState', () => {
+      const tracker = createTracker(createState(1))
+      const changed = createState(2)
+      mockCanvasState(changed)
+
+      tracker.checkState()
+
+      expect(tracker.activeState).toEqual(changed)
+    })
+  })
+})