overleaf/services/web/test/frontend/shared/hooks/use-persisted-state.test.tsx

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import sinon from 'sinon'
import { expect } from 'chai'
import { useEffect } from 'react'
import { render, screen } from '@testing-library/react'
import usePersistedState from '../../../../frontend/js/shared/hooks/use-persisted-state'
import localStorage from '../../../../frontend/js/infrastructure/local-storage'
describe('usePersistedState', function () {
beforeEach(function () {
sinon.spy(window.Storage.prototype, 'getItem')
sinon.spy(window.Storage.prototype, 'removeItem')
sinon.spy(window.Storage.prototype, 'setItem')
})
afterEach(function () {
sinon.restore()
})
it('reads the value from localStorage', function () {
const key = 'test'
localStorage.setItem(key, 'foo')
expect(window.Storage.prototype.setItem).to.have.callCount(1)
const Test = () => {
const [value] = usePersistedState(key)
return <div>{value}</div>
}
render(<Test />)
screen.getByText('foo')
expect(window.Storage.prototype.getItem).to.have.callCount(1)
expect(window.Storage.prototype.removeItem).to.have.callCount(0)
expect(window.Storage.prototype.setItem).to.have.callCount(1)
expect(localStorage.getItem(key)).to.equal('foo')
})
it('uses the default value without storing anything', function () {
const key = 'test:default'
const Test = () => {
const [value] = usePersistedState(key, 'foo')
return <div>{value}</div>
}
render(<Test />)
screen.getByText('foo')
expect(window.Storage.prototype.getItem).to.have.callCount(1)
expect(window.Storage.prototype.removeItem).to.have.callCount(0)
expect(window.Storage.prototype.setItem).to.have.callCount(0)
expect(localStorage.getItem(key)).to.be.null
})
it('stores the new value in localStorage', function () {
const key = 'test:store'
localStorage.setItem(key, 'foo')
expect(window.Storage.prototype.setItem).to.have.callCount(1)
const Test = () => {
const [value, setValue] = usePersistedState(key, 'bar')
useEffect(() => {
setValue('baz')
}, [setValue])
return <div>{value}</div>
}
render(<Test />)
screen.getByText('baz')
expect(window.Storage.prototype.getItem).to.have.callCount(1)
expect(window.Storage.prototype.removeItem).to.have.callCount(0)
expect(window.Storage.prototype.setItem).to.have.callCount(2)
expect(localStorage.getItem(key)).to.equal('baz')
})
it('removes the value from localStorage if it equals the default value', function () {
const key = 'test:store-default'
localStorage.setItem(key, 'foo')
expect(window.Storage.prototype.setItem).to.have.callCount(1)
const Test = () => {
const [value, setValue] = usePersistedState(key, 'bar')
useEffect(() => {
// set a different value
setValue('baz')
expect(localStorage.getItem(key)).to.equal('baz')
// set the default value again
setValue('bar')
}, [setValue])
return <div>{value}</div>
}
render(<Test />)
screen.getByText('bar')
expect(window.Storage.prototype.getItem).to.have.callCount(2)
expect(window.Storage.prototype.removeItem).to.have.callCount(1)
expect(window.Storage.prototype.setItem).to.have.callCount(2)
expect(localStorage.getItem(key)).to.be.null
})
it('handles function values', function () {
const key = 'test:store'
localStorage.setItem(key, 'foo')
expect(window.Storage.prototype.setItem).to.have.callCount(1)
const Test = () => {
const [value, setValue] = usePersistedState(key)
useEffect(() => {
setValue(value => value + 'bar')
}, [setValue])
return <div>{value}</div>
}
render(<Test />)
screen.getByText('foobar')
expect(window.Storage.prototype.getItem).to.have.callCount(1)
expect(window.Storage.prototype.removeItem).to.have.callCount(0)
expect(window.Storage.prototype.setItem).to.have.callCount(2)
expect(localStorage.getItem(key)).to.equal('foobar')
})
it('handles syncing values via storage event', async function () {
const key = 'test:sync'
localStorage.setItem(key, 'foo')
expect(window.Storage.prototype.setItem).to.have.callCount(1)
// listen for storage events
const storageEventListener = sinon.stub()
window.addEventListener('storage', storageEventListener)
const Test = () => {
const [value, setValue] = usePersistedState(key, 'bar', true)
useEffect(() => {
setValue('baz')
}, [setValue])
return <div>{value}</div>
}
render(<Test />)
screen.getByText('baz')
expect(window.Storage.prototype.getItem).to.have.callCount(1)
expect(window.Storage.prototype.removeItem).to.have.callCount(0)
expect(window.Storage.prototype.setItem).to.have.callCount(2)
expect(localStorage.getItem(key)).to.equal('baz')
expect(storageEventListener).to.have.callCount(0)
// set the new value in localStorage
localStorage.setItem(key, 'cat')
// dispatch a "storage" event and check that it's picked up by the hook
window.dispatchEvent(new StorageEvent('storage', { key }))
await screen.findByText('cat')
expect(storageEventListener).to.have.callCount(1)
})
})