core/packages/runtime-core/__tests__/hydration.spec.ts

import {
  createSSRApp,
  h,
  ref,
  nextTick,
  VNode,
  Portal,
  createStaticVNode,
  Suspense,
  onMounted
} from '@vue/runtime-dom'
import { renderToString } from '@vue/server-renderer'
import { mockWarn } from '@vue/shared'

function mountWithHydration(html: string, render: () => any) {
  const container = document.createElement('div')
  container.innerHTML = html
  const app = createSSRApp({
    render
  })
  return {
    vnode: app.mount(container).$.subTree,
    container
  }
}

const triggerEvent = (type: string, el: Element) => {
  const event = new Event(type)
  el.dispatchEvent(event)
}

describe('SSR hydration', () => {
  mockWarn()

  test('text', async () => {
    const msg = ref('foo')
    const { vnode, container } = mountWithHydration('foo', () => msg.value)
    expect(vnode.el).toBe(container.firstChild)
    expect(container.textContent).toBe('foo')
    msg.value = 'bar'
    await nextTick()
    expect(container.textContent).toBe('bar')
  })

  test('comment', () => {
    const { vnode, container } = mountWithHydration('<!---->', () => null)
    expect(vnode.el).toBe(container.firstChild)
    expect(vnode.el.nodeType).toBe(8) // comment
  })

  test('static', () => {
    const html = '<div><span>hello</span></div>'
    const { vnode, container } = mountWithHydration(html, () =>
      createStaticVNode(html)
    )
    expect(vnode.el).toBe(container.firstChild)
    expect(vnode.el.outerHTML).toBe(html)
  })

  test('element with text children', async () => {
    const msg = ref('foo')
    const { vnode, container } = mountWithHydration(
      '<div class="foo">foo</div>',
      () => h('div', { class: msg.value }, msg.value)
    )
    expect(vnode.el).toBe(container.firstChild)
    expect(container.firstChild!.textContent).toBe('foo')
    msg.value = 'bar'
    await nextTick()
    expect(container.innerHTML).toBe(`<div class="bar">bar</div>`)
  })

  test('element with elements children', async () => {
    const msg = ref('foo')
    const fn = jest.fn()
    const { vnode, container } = mountWithHydration(
      '<div><span>foo</span><span class="foo"></span></div>',
      () =>
        h('div', [
          h('span', msg.value),
          h('span', { class: msg.value, onClick: fn })
        ])
    )
    expect(vnode.el).toBe(container.firstChild)
    expect((vnode.children as VNode[])[0].el).toBe(
      container.firstChild!.childNodes[0]
    )
    expect((vnode.children as VNode[])[1].el).toBe(
      container.firstChild!.childNodes[1]
    )

    // event handler
    triggerEvent('click', vnode.el.querySelector('.foo'))
    expect(fn).toHaveBeenCalled()

    msg.value = 'bar'
    await nextTick()
    expect(vnode.el.innerHTML).toBe(`<span>bar</span><span class="bar"></span>`)
  })

  test('Fragment', async () => {
    const msg = ref('foo')
    const fn = jest.fn()
    const { vnode, container } = mountWithHydration(
      '<div><!--[--><span>foo</span><!--[--><span class="foo"></span><!--]--><!--]--></div>',
      () =>
        h('div', [
          [h('span', msg.value), [h('span', { class: msg.value, onClick: fn })]]
        ])
    )
    expect(vnode.el).toBe(container.firstChild)

    expect(vnode.el.innerHTML).toBe(
      `<!--[--><span>foo</span><!--[--><span class="foo"></span><!--]--><!--]-->`
    )

    // start fragment 1
    const fragment1 = (vnode.children as VNode[])[0]
    expect(fragment1.el).toBe(vnode.el.childNodes[0])
    const fragment1Children = fragment1.children as VNode[]

    // first <span>
    expect(fragment1Children[0].el.tagName).toBe('SPAN')
    expect(fragment1Children[0].el).toBe(vnode.el.childNodes[1])

    // start fragment 2
    const fragment2 = fragment1Children[1]
    expect(fragment2.el).toBe(vnode.el.childNodes[2])
    const fragment2Children = fragment2.children as VNode[]

    // second <span>
    expect(fragment2Children[0].el.tagName).toBe('SPAN')
    expect(fragment2Children[0].el).toBe(vnode.el.childNodes[3])

    // end fragment 2
    expect(fragment2.anchor).toBe(vnode.el.childNodes[4])

    // end fragment 1
    expect(fragment1.anchor).toBe(vnode.el.childNodes[5])

    // event handler
    triggerEvent('click', vnode.el.querySelector('.foo'))
    expect(fn).toHaveBeenCalled()

    msg.value = 'bar'
    await nextTick()
    expect(vnode.el.innerHTML).toBe(
      `<!--[--><span>bar</span><!--[--><span class="bar"></span><!--]--><!--]-->`
    )
  })

  test('Portal', async () => {
    const msg = ref('foo')
    const fn = jest.fn()
    const portalContainer = document.createElement('div')
    portalContainer.id = 'portal'
    portalContainer.innerHTML = `<span>foo</span><span class="foo"></span>`
    document.body.appendChild(portalContainer)

    const { vnode, container } = mountWithHydration('<!--portal-->', () =>
      h(Portal, { target: '#portal' }, [
        h('span', msg.value),
        h('span', { class: msg.value, onClick: fn })
      ])
    )

    expect(vnode.el).toBe(container.firstChild)
    expect((vnode.children as VNode[])[0].el).toBe(
      portalContainer.childNodes[0]
    )
    expect((vnode.children as VNode[])[1].el).toBe(
      portalContainer.childNodes[1]
    )

    // event handler
    triggerEvent('click', portalContainer.querySelector('.foo')!)
    expect(fn).toHaveBeenCalled()

    msg.value = 'bar'
    await nextTick()
    expect(portalContainer.innerHTML).toBe(
      `<span>bar</span><span class="bar"></span>`
    )
  })

  // compile SSR + client render fn from the same template & hydrate
  test('full compiler integration', async () => {
    const mounted: string[] = []
    const log = jest.fn()
    const toggle = ref(true)

    const Child = {
      data() {
        return {
          count: 0,
          text: 'hello',
          style: {
            color: 'red'
          }
        }
      },
      mounted() {
        mounted.push('child')
      },
      template: `
      <div>
        <span class="count" :style="style">{{ count }}</span>
        <button class="inc" @click="count++">inc</button>
        <button class="change" @click="style.color = 'green'" >change color</button>
        <button class="emit" @click="$emit('foo')">emit</button>
        <span class="text">{{ text }}</span>
        <input v-model="text">
      </div>
      `
    }

    const App = {
      setup() {
        return { toggle }
      },
      mounted() {
        mounted.push('parent')
      },
      template: `
        <div>
          <span>hello</span>
          <template v-if="toggle">
            <Child @foo="log('child')"/>
            <template v-if="true">
              <button class="parent-click" @click="log('click')">click me</button>
            </template>
          </template>
          <span>hello</span>
        </div>`,
      components: {
        Child
      },
      methods: {
        log
      }
    }

    const container = document.createElement('div')
    // server render
    container.innerHTML = await renderToString(h(App))
    // hydrate
    createSSRApp(App).mount(container)

    // assert interactions
    // 1. parent button click
    triggerEvent('click', container.querySelector('.parent-click')!)
    expect(log).toHaveBeenCalledWith('click')

    // 2. child inc click + text interpolation
    const count = container.querySelector('.count') as HTMLElement
    expect(count.textContent).toBe(`0`)
    triggerEvent('click', container.querySelector('.inc')!)
    await nextTick()
    expect(count.textContent).toBe(`1`)

    // 3. child color click + style binding
    expect(count.style.color).toBe('red')
    triggerEvent('click', container.querySelector('.change')!)
    await nextTick()
    expect(count.style.color).toBe('green')

    // 4. child event emit
    triggerEvent('click', container.querySelector('.emit')!)
    expect(log).toHaveBeenCalledWith('child')

    // 5. child v-model
    const text = container.querySelector('.text')!
    const input = container.querySelector('input')!
    expect(text.textContent).toBe('hello')
    input.value = 'bye'
    triggerEvent('input', input)
    await nextTick()
    expect(text.textContent).toBe('bye')
  })

  test('Suspense', async () => {
    const AsyncChild = {
      async setup() {
        const count = ref(0)
        return () =>
          h(
            'span',
            {
              onClick: () => {
                count.value++
              }
            },
            count.value
          )
      }
    }
    const { vnode, container } = mountWithHydration('<span>0</span>', () =>
      h(Suspense, () => h(AsyncChild))
    )
    expect(vnode.el).toBe(container.firstChild)
    // wait for hydration to finish
    await new Promise(r => setTimeout(r))
    triggerEvent('click', container.querySelector('span')!)
    await nextTick()
    expect(container.innerHTML).toBe(`<span>1</span>`)
  })

  test('Suspense (full integration)', async () => {
    const mountedCalls: number[] = []
    const asyncDeps: Promise<any>[] = []

    const AsyncChild = {
      async setup(props: { n: number }) {
        const count = ref(props.n)
        onMounted(() => {
          mountedCalls.push(props.n)
        })
        const p = new Promise(r => setTimeout(r, props.n * 10))
        asyncDeps.push(p)
        await p
        return () =>
          h(
            'span',
            {
              onClick: () => {
                count.value++
              }
            },
            count.value
          )
      }
    }

    const done = jest.fn()
    const App = {
      template: `
      <Suspense @resolve="done">
        <AsyncChild :n="1" />
        <AsyncChild :n="2" />
      </Suspense>`,
      components: {
        AsyncChild
      },
      methods: {
        done
      }
    }

    const container = document.createElement('div')
    // server render
    container.innerHTML = await renderToString(h(App))
    expect(container.innerHTML).toMatchInlineSnapshot(
      `"<!--[--><span>1</span><span>2</span><!--]-->"`
    )
    // reset asyncDeps from ssr
    asyncDeps.length = 0
    // hydrate
    createSSRApp(App).mount(container)

    expect(mountedCalls.length).toBe(0)
    expect(asyncDeps.length).toBe(2)

    // wait for hydration to complete
    await Promise.all(asyncDeps)
    await new Promise(r => setTimeout(r))

    // should flush buffered effects
    expect(mountedCalls).toMatchObject([1, 2])
    expect(container.innerHTML).toMatch(`<span>1</span><span>2</span>`)

    const span1 = container.querySelector('span')!
    triggerEvent('click', span1)
    await nextTick()
    expect(container.innerHTML).toMatch(`<span>2</span><span>2</span>`)

    const span2 = span1.nextSibling as Element
    triggerEvent('click', span2)
    await nextTick()
    expect(container.innerHTML).toMatch(`<span>2</span><span>3</span>`)
  })

  describe('mismatch handling', () => {
    test('text node', () => {
      const { container } = mountWithHydration(`foo`, () => 'bar')
      expect(container.textContent).toBe('bar')
      expect(`Hydration text mismatch`).toHaveBeenWarned()
    })

    test('element text content', () => {
      const { container } = mountWithHydration(`<div>foo</div>`, () =>
        h('div', 'bar')
      )
      expect(container.innerHTML).toBe('<div>bar</div>')
      expect(`Hydration text content mismatch in <div>`).toHaveBeenWarned()
    })

    test('not enough children', () => {
      const { container } = mountWithHydration(`<div></div>`, () =>
        h('div', [h('span', 'foo'), h('span', 'bar')])
      )
      expect(container.innerHTML).toBe(
        '<div><span>foo</span><span>bar</span></div>'
      )
      expect(`Hydration children mismatch in <div>`).toHaveBeenWarned()
    })

    test('too many children', () => {
      const { container } = mountWithHydration(
        `<div><span>foo</span><span>bar</span></div>`,
        () => h('div', [h('span', 'foo')])
      )
      expect(container.innerHTML).toBe('<div><span>foo</span></div>')
      expect(`Hydration children mismatch in <div>`).toHaveBeenWarned()
    })

    test('complete mismatch', () => {
      const { container } = mountWithHydration(
        `<div><span>foo</span><span>bar</span></div>`,
        () => h('div', [h('div', 'foo'), h('p', 'bar')])
      )
      expect(container.innerHTML).toBe('<div><div>foo</div><p>bar</p></div>')
      expect(`Hydration node mismatch`).toHaveBeenWarnedTimes(2)
    })

    test('fragment mismatch removal', () => {
      const { container } = mountWithHydration(
        `<div><!--[--><div>foo</div><div>bar</div><!--]--></div>`,
        () => h('div', [h('span', 'replaced')])
      )
      expect(container.innerHTML).toBe('<div><span>replaced</span></div>')
      expect(`Hydration node mismatch`).toHaveBeenWarned()
    })

    test('fragment not enough children', () => {
      const { container } = mountWithHydration(
        `<div><!--[--><div>foo</div><!--]--><div>baz</div></div>`,
        () => h('div', [[h('div', 'foo'), h('div', 'bar')], h('div', 'baz')])
      )
      expect(container.innerHTML).toBe(
        '<div><!--[--><div>foo</div><div>bar</div><!--]--><div>baz</div></div>'
      )
      expect(`Hydration node mismatch`).toHaveBeenWarned()
    })

    test('fragment too many children', () => {
      const { container } = mountWithHydration(
        `<div><!--[--><div>foo</div><div>bar</div><!--]--><div>baz</div></div>`,
        () => h('div', [[h('div', 'foo')], h('div', 'baz')])
      )
      expect(container.innerHTML).toBe(
        '<div><!--[--><div>foo</div><!--]--><div>baz</div></div>'
      )
      // fragment ends early and attempts to hydrate the extra <div>bar</div>
      // as 2nd fragment child.
      expect(`Hydration text content mismatch`).toHaveBeenWarned()
      // exccesive children removal
      expect(`Hydration children mismatch`).toHaveBeenWarned()
    })
  })
})