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useDetectScroll.test.ts
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203 lines (170 loc) · 6.37 KB
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import {act, renderHook, waitFor} from '@testing-library/react'
import {beforeEach, describe, expect, it, vi} from 'vitest'
import useDetectScroll from './useDetectScroll'
import {Axis, Direction} from './useDetectScroll.types'
const setNumericProp = (obj: HTMLElement, key: string, value: number) => {
Object.defineProperty(obj, key, {configurable: true, value})
}
const createScrollableDiv = () => {
const div = document.createElement('div')
setNumericProp(div, 'scrollTop', 0)
setNumericProp(div, 'scrollLeft', 0)
setNumericProp(div, 'scrollHeight', 1000)
setNumericProp(div, 'scrollWidth', 800)
setNumericProp(div, 'clientHeight', 200)
setNumericProp(div, 'clientWidth', 300)
return div
}
describe('useDetectScroll', () => {
beforeEach(() => {
vi.restoreAllMocks()
vi.spyOn(window, 'requestAnimationFrame').mockImplementation(cb => {
cb(0)
return 0
})
})
it('reports initial scroll position for a target element', async () => {
const target = createScrollableDiv()
setNumericProp(target, 'scrollTop', 100)
setNumericProp(target, 'scrollLeft', 40)
const {result} = renderHook(() => useDetectScroll({target}))
await waitFor(() => {
expect(result.current.scrollPosition.top).toBe(100)
expect(result.current.scrollPosition.left).toBe(40)
expect(result.current.scrollPosition.bottom).toBe(700)
expect(result.current.scrollPosition.right).toBe(460)
})
})
it('detects vertical scroll direction', async () => {
const target = createScrollableDiv()
const {result} = renderHook(() =>
useDetectScroll({target, axis: Axis.Y}),
)
act(() => {
setNumericProp(target, 'scrollTop', 120)
target.dispatchEvent(new Event('scroll'))
})
await waitFor(() => {
expect(result.current.scrollDir).toBe(Direction.Down)
})
})
it('detects horizontal scroll direction', async () => {
const target = createScrollableDiv()
const {result} = renderHook(() =>
useDetectScroll({target, axis: Axis.X}),
)
act(() => {
setNumericProp(target, 'scrollLeft', 90)
target.dispatchEvent(new Event('scroll'))
})
await waitFor(() => {
expect(result.current.scrollDir).toBe(Direction.Right)
})
})
it('respects the threshold before changing direction', async () => {
const target = createScrollableDiv()
const {result} = renderHook(() =>
useDetectScroll({target, axis: Axis.Y, thr: 50}),
)
act(() => {
setNumericProp(target, 'scrollTop', 20)
target.dispatchEvent(new Event('scroll'))
})
await waitFor(() => {
expect(result.current.scrollDir).toBe(Direction.Still)
})
})
it('uses custom direction values when provided', async () => {
const target = createScrollableDiv()
const {result} = renderHook(() =>
useDetectScroll({
target,
axis: Axis.Y,
scrollUp: Direction.Left,
scrollDown: Direction.Right,
still: Direction.Still,
}),
)
act(() => {
setNumericProp(target, 'scrollTop', 80)
target.dispatchEvent(new Event('scroll'))
})
await waitFor(() => {
expect(result.current.scrollDir).toBe(Direction.Right)
})
})
it('clamps negative thresholds to zero', async () => {
const target = createScrollableDiv()
const {result} = renderHook(() =>
useDetectScroll({target, axis: Axis.Y, thr: -10}),
)
act(() => {
setNumericProp(target, 'scrollTop', 1)
target.dispatchEvent(new Event('scroll'))
})
await waitFor(() => {
expect(result.current.scrollDir).toBe(Direction.Down)
})
})
it('computes scroll position for window target', async () => {
const prevWindowCtor = globalThis.Window
;(globalThis as {Window?: typeof Window}).Window =
window.constructor as typeof Window
let winScrollY = 0
let winScrollX = 0
const prevScrollY = Object.getOwnPropertyDescriptor(window, 'scrollY')
const prevScrollX = Object.getOwnPropertyDescriptor(window, 'scrollX')
Object.defineProperty(window, 'scrollY', {
configurable: true,
get: () => winScrollY,
})
Object.defineProperty(window, 'scrollX', {
configurable: true,
get: () => winScrollX,
})
Object.defineProperty(window, 'innerHeight', {
configurable: true,
value: 200,
})
Object.defineProperty(window, 'innerWidth', {
configurable: true,
value: 300,
})
Object.defineProperty(document.documentElement, 'scrollHeight', {
configurable: true,
value: 1000,
})
Object.defineProperty(document.documentElement, 'scrollWidth', {
configurable: true,
value: 800,
})
const {result} = renderHook(() => useDetectScroll())
act(() => {
winScrollY = 120
winScrollX = 30
window.dispatchEvent(new Event('scroll'))
})
await waitFor(() => {
expect(result.current.scrollPosition.top).toBe(120)
expect(result.current.scrollPosition.left).toBe(30)
expect(result.current.scrollPosition.bottom).toBe(680)
expect(result.current.scrollPosition.right).toBe(470)
})
if (prevScrollY) {
Object.defineProperty(window, 'scrollY', prevScrollY)
} else {
delete (window as {scrollY?: number}).scrollY
}
if (prevScrollX) {
Object.defineProperty(window, 'scrollX', prevScrollX)
} else {
delete (window as {scrollX?: number}).scrollX
}
;(globalThis as {Window?: typeof Window}).Window = prevWindowCtor
})
it('warns when target is missing', () => {
const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {})
renderHook(() => useDetectScroll({target: null as unknown as Window}))
expect(warnSpy).toHaveBeenCalled()
})
})