chore: migrate tests from tests-ui/ to colocate with source files (#7811)

## Summary

Migrates all unit tests from `tests-ui/` to colocate with their source
files in `src/`, improving discoverability and maintainability.

## Changes

- **What**: Relocated all unit tests to be adjacent to the code they
test, following the `<source>.test.ts` naming convention
- **Config**: Updated `vitest.config.ts` to remove `tests-ui` include
pattern and `@tests-ui` alias
- **Docs**: Moved testing documentation to `docs/testing/` with updated
paths and patterns

## Review Focus

- Migration patterns documented in
`temp/plans/migrate-tests-ui-to-src.md`
- Tests use `@/` path aliases instead of relative imports
- Shared fixtures placed in `__fixtures__/` directories

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7811-chore-migrate-tests-from-tests-ui-to-colocate-with-source-files-2da6d73d36508147a4cce85365dee614)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Amp <amp@ampcode.com>
Co-authored-by: GitHub Action <action@github.com>

src/renderer/core/canvas/useCanvasInteractions.test.ts

@@ -0,0 +1,159 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+import type { LGraphCanvas } from '@/lib/litegraph/src/litegraph'
+import { useSettingStore } from '@/platform/settings/settingStore'
+import { useCanvasStore } from '@/renderer/core/canvas/canvasStore'
+import { useCanvasInteractions } from '@/renderer/core/canvas/useCanvasInteractions'
+
+// Mock stores
+vi.mock('@/renderer/core/canvas/canvasStore', () => {
+  const getCanvas = vi.fn()
+  const setCursorStyle = vi.fn()
+  return {
+    useCanvasStore: vi.fn(() => ({
+      getCanvas,
+      setCursorStyle
+    }))
+  }
+})
+vi.mock('@/platform/settings/settingStore', () => {
+  const getFn = vi.fn()
+  return { useSettingStore: vi.fn(() => ({ get: getFn })) }
+})
+vi.mock('@/scripts/app', () => ({
+  app: {
+    canvas: {
+      canvas: {
+        dispatchEvent: vi.fn()
+      }
+    }
+  }
+}))
+
+function createMockLGraphCanvas(read_only = true): LGraphCanvas {
+  const mockCanvas: Partial<LGraphCanvas> = { read_only }
+  return mockCanvas as LGraphCanvas
+}
+
+function createMockPointerEvent(
+  buttons: PointerEvent['buttons'] = 1
+): PointerEvent {
+  const mockEvent: Partial<PointerEvent> = {
+    buttons,
+    preventDefault: vi.fn(),
+    stopPropagation: vi.fn()
+  }
+  return mockEvent as PointerEvent
+}
+
+function createMockWheelEvent(ctrlKey = false, metaKey = false): WheelEvent {
+  const mockEvent: Partial<WheelEvent> = {
+    ctrlKey,
+    metaKey,
+    preventDefault: vi.fn(),
+    stopPropagation: vi.fn()
+  }
+  return mockEvent as WheelEvent
+}
+
+describe('useCanvasInteractions', () => {
+  beforeEach(() => {
+    vi.resetAllMocks()
+  })
+
+  describe('handlePointer', () => {
+    it('should intercept left mouse events when canvas is read_only to enable space+drag navigation', () => {
+      const { getCanvas } = useCanvasStore()
+      const mockCanvas = createMockLGraphCanvas(true)
+      vi.mocked(getCanvas).mockReturnValue(mockCanvas)
+
+      const { handlePointer } = useCanvasInteractions()
+
+      const mockEvent = createMockPointerEvent(1) // Left Mouse Button
+      handlePointer(mockEvent)
+
+      expect(mockEvent.preventDefault).toHaveBeenCalled()
+      expect(mockEvent.stopPropagation).toHaveBeenCalled()
+    })
+
+    it('should forward middle mouse button events to canvas', () => {
+      const { getCanvas } = useCanvasStore()
+      const mockCanvas = createMockLGraphCanvas(false)
+      vi.mocked(getCanvas).mockReturnValue(mockCanvas)
+      const { handlePointer } = useCanvasInteractions()
+
+      const mockEvent = createMockPointerEvent(4) // Middle mouse button
+      handlePointer(mockEvent)
+
+      expect(mockEvent.preventDefault).toHaveBeenCalled()
+      expect(mockEvent.stopPropagation).toHaveBeenCalled()
+    })
+
+    it('should not prevent default when canvas is not in read_only mode and not middle button', () => {
+      const { getCanvas } = useCanvasStore()
+      const mockCanvas = createMockLGraphCanvas(false)
+      vi.mocked(getCanvas).mockReturnValue(mockCanvas)
+      const { handlePointer } = useCanvasInteractions()
+
+      const mockEvent = createMockPointerEvent(1)
+      handlePointer(mockEvent)
+
+      expect(mockEvent.preventDefault).not.toHaveBeenCalled()
+      expect(mockEvent.stopPropagation).not.toHaveBeenCalled()
+    })
+
+    it('should return early when canvas is null', () => {
+      const { getCanvas } = useCanvasStore()
+      vi.mocked(getCanvas).mockReturnValue(null as unknown as LGraphCanvas) // TODO: Fix misaligned types
+      const { handlePointer } = useCanvasInteractions()
+
+      const mockEvent = createMockPointerEvent(1)
+      handlePointer(mockEvent)
+
+      expect(getCanvas).toHaveBeenCalled()
+      expect(mockEvent.preventDefault).not.toHaveBeenCalled()
+      expect(mockEvent.stopPropagation).not.toHaveBeenCalled()
+    })
+  })
+
+  describe('handleWheel', () => {
+    it('should forward ctrl+wheel events to canvas in standard nav mode', () => {
+      const { get } = useSettingStore()
+      vi.mocked(get).mockReturnValue('standard')
+
+      const { handleWheel } = useCanvasInteractions()
+
+      // Ctrl key pressed
+      const mockEvent = createMockWheelEvent(true)
+
+      handleWheel(mockEvent)
+
+      expect(mockEvent.preventDefault).toHaveBeenCalled()
+      expect(mockEvent.stopPropagation).toHaveBeenCalled()
+    })
+
+    it('should forward all wheel events to canvas in legacy nav mode', () => {
+      const { get } = useSettingStore()
+      vi.mocked(get).mockReturnValue('legacy')
+      const { handleWheel } = useCanvasInteractions()
+
+      const mockEvent = createMockWheelEvent()
+      handleWheel(mockEvent)
+
+      expect(mockEvent.preventDefault).toHaveBeenCalled()
+      expect(mockEvent.stopPropagation).toHaveBeenCalled()
+    })
+
+    it('should not prevent default for regular wheel events in standard nav mode', () => {
+      const { get } = useSettingStore()
+      vi.mocked(get).mockReturnValue('standard')
+      const { handleWheel } = useCanvasInteractions()
+
+      const mockEvent = createMockWheelEvent()
+      handleWheel(mockEvent)
+
+      expect(mockEvent.preventDefault).not.toHaveBeenCalled()
+      expect(mockEvent.stopPropagation).not.toHaveBeenCalled()
+    })
+  })
+})