component-slot.spec.js

import Vue from 'vue'

describe('Component slot', () => {
  let vm, child
  function mount (options) {
    vm = new Vue({
      data: {
        msg: 'parent message'
      },
      template: `<div><test>${options.parentContent || ''}</test></div>`,
      components: {
        test: {
          template: options.childTemplate,
          data () {
            return {
              msg: 'child message'
            }
          }
        }
      }
    }).$mount()
    child = vm.$children[0]
  }

  it('no content', () => {
    mount({
      childTemplate: '<div><slot></slot></div>'
    })
    expect(child.$el.childNodes.length).toBe(0)
  })

  it('default slot', done => {
    mount({
      childTemplate: '<div><slot></slot></div>',
      parentContent: '<p>{{ msg }}</p>'
    })
    expect(child.$el.tagName).toBe('DIV')
    expect(child.$el.children[0].tagName).toBe('P')
    expect(child.$el.children[0].textContent).toBe('parent message')
    vm.msg = 'changed'
    waitForUpdate(() => {
      expect(child.$el.children[0].textContent).toBe('changed')
    }).then(done)
  })

  it('named slot', done => {
    mount({
      childTemplate: '<div><slot name="test"></slot></div>',
      parentContent: '<p slot="test">{{ msg }}</p>'
    })
    expect(child.$el.tagName).toBe('DIV')
    expect(child.$el.children[0].tagName).toBe('P')
    expect(child.$el.children[0].textContent).toBe('parent message')
    vm.msg = 'changed'
    waitForUpdate(() => {
      expect(child.$el.children[0].textContent).toBe('changed')
    }).then(done)
  })

  it('named slot with 0 as a number', done => {
    mount({
      childTemplate: '<div><slot :name="0"></slot></div>',
      parentContent: '<p :slot="0">{{ msg }}</p>'
    })
    expect(child.$el.tagName).toBe('DIV')
    expect(child.$el.children[0].tagName).toBe('P')
    expect(child.$el.children[0].textContent).toBe('parent message')
    vm.msg = 'changed'
    waitForUpdate(() => {
      expect(child.$el.children[0].textContent).toBe('changed')
    }).then(done)
  })

  it('fallback content', () => {
    mount({
      childTemplate: '<div><slot><p>{{msg}}</p></slot></div>'
    })
    expect(child.$el.children[0].tagName).toBe('P')
    expect(child.$el.textContent).toBe('child message')
  })

  it('fallback content with multiple named slots', () => {
    mount({
      childTemplate: `
        <div>
          <slot name="a"><p>fallback a</p></slot>
          <slot name="b">fallback b</slot>
        </div>
      `,
      parentContent: '<p slot="b">slot b</p>'
    })
    expect(child.$el.children.length).toBe(2)
    expect(child.$el.children[0].textContent).toBe('fallback a')
    expect(child.$el.children[1].textContent).toBe('slot b')
  })

  it('fallback content with mixed named/unnamed slots', () => {
    mount({
      childTemplate: `
        <div>
          <slot><p>fallback a</p></slot>
          <slot name="b">fallback b</slot>
        </div>
      `,
      parentContent: '<p slot="b">slot b</p>'
    })
    expect(child.$el.children.length).toBe(2)
    expect(child.$el.children[0].textContent).toBe('fallback a')
    expect(child.$el.children[1].textContent).toBe('slot b')
  })

 it('it should work with previous versions of the templates', () => {
   const Test = {
      render() {
        var _vm = this;
        var _h = _vm.$createElement;
        var _c = _vm._self._c || vm._h;
        return _c('div', [_vm._t("default", [_c('p', [_vm._v("slot default")])])], 2)
      }
    }
    let vm = new Vue({
      template: `<test/>`,
      components: { Test }
    }).$mount()
    expect(vm.$el.textContent).toBe('slot default')
    vm = new Vue({
      template: `<test>custom content</test>`,
      components: { Test }
    }).$mount()
    expect(vm.$el.textContent).toBe('custom content')
  })

  it('fallback content should not be evaluated when the parent is providing it', () => {
    const test = jasmine.createSpy('test')
    const vm = new Vue({
      template: '<test>slot default</test>',
      components: {
        test: {
          template: '<div><slot>{{test()}}</slot></div>',
          methods: {
            test () {
              test()
              return 'test'
            }
          }
        }
      }
    }).$mount()
    expect(vm.$el.textContent).toBe('slot default')
    expect(test).not.toHaveBeenCalled()
  })

  it('selector matching multiple elements', () => {
    mount({
      childTemplate: '<div><slot name="t"></slot></div>',
      parentContent: '<p slot="t">1</p><div></div><p slot="t">2</p>'
    })
    expect(child.$el.innerHTML).toBe('<p>1</p><p>2</p>')
  })

  it('default content should only render parts not selected', () => {
    mount({
      childTemplate: `
        <div>
          <slot name="a"></slot>
          <slot></slot>
          <slot name="b"></slot>
        </div>
      `,
      parentContent: '<div>foo</div><p slot="a">1</p><p slot="b">2</p>'
    })
    expect(child.$el.innerHTML).toBe('<p>1</p> <div>foo</div> <p>2</p>')
  })

  it('name should only match children', function () {
    mount({
      childTemplate: `
        <div>
          <slot name="a"><p>fallback a</p></slot>
          <slot name="b"><p>fallback b</p></slot>
          <slot name="c"><p>fallback c</p></slot>
        </div>
      `,
      parentContent: `
        '<p slot="b">select b</p>
        '<span><p slot="b">nested b</p></span>
        '<span><p slot="c">nested c</p></span>
      `
    })
    expect(child.$el.children.length).toBe(3)
    expect(child.$el.children[0].textContent).toBe('fallback a')
    expect(child.$el.children[1].textContent).toBe('select b')
    expect(child.$el.children[2].textContent).toBe('fallback c')
  })

  it('should accept expressions in slot attribute and slot names', () => {
    mount({
      childTemplate: `<div><slot :name="'a'"></slot></div>`,
      parentContent: `<p>one</p><p :slot="'a'">two</p>`
    })
    expect(child.$el.innerHTML).toBe('<p>two</p>')
  })

  it('slot inside v-if', done => {
    const vm = new Vue({
      data: {
        a: 1,
        b: 2,
        show: true
      },
      template: '<test :show="show"><p slot="b">{{b}}</p><p>{{a}}</p></test>',
      components: {
        test: {
          props: ['show'],
          template: '<div v-if="show"><slot></slot><slot name="b"></slot></div>'
        }
      }
    }).$mount()
    expect(vm.$el.textContent).toBe('12')
    vm.a = 2
    waitForUpdate(() => {
      expect(vm.$el.textContent).toBe('22')
      vm.show = false
    }).then(() => {
      expect(vm.$el.textContent).toBe('')
      vm.show = true
      vm.a = 3
    }).then(() => {
      expect(vm.$el.textContent).toBe('32')
    }).then(done)
  })

  it('slot inside v-for', () => {
    mount({
      childTemplate: '<div><slot v-for="i in 3" :name="i"></slot></div>',
      parentContent: '<p v-for="i in 3" :slot="i">{{ i - 1 }}</p>'
    })
    expect(child.$el.innerHTML).toBe('<p>0</p><p>1</p><p>2</p>')
  })

  it('nested slots', done => {
    const vm = new Vue({
      template: '<test><test2><p>{{ msg }}</p></test2></test>',
      data: {
        msg: 'foo'
      },
      components: {
        test: {
          template: '<div><slot></slot></div>'
        },
        test2: {
          template: '<div><slot></slot></div>'
        }
      }
    }).$mount()
    expect(vm.$el.innerHTML).toBe('<div><p>foo</p></div>')
    vm.msg = 'bar'
    waitForUpdate(() => {
      expect(vm.$el.innerHTML).toBe('<div><p>bar</p></div>')
    }).then(done)
  })

  it('v-if on inserted content', done => {
    const vm = new Vue({
      template: '<test><p v-if="ok">{{ msg }}</p></test>',
      data: {
        ok: true,
        msg: 'hi'
      },
      components: {
        test: {
          template: '<div><slot>fallback</slot></div>'
        }
      }
    }).$mount()
    expect(vm.$el.innerHTML).toBe('<p>hi</p>')
    vm.ok = false
    waitForUpdate(() => {
      expect(vm.$el.innerHTML).toBe('fallback')
      vm.ok = true
      vm.msg = 'bye'
    }).then(() => {
      expect(vm.$el.innerHTML).toBe('<p>bye</p>')
    }).then(done)
  })

  it('template slot', function () {
    const vm = new Vue({
      template: '<test><template slot="test">hello</template></test>',
      components: {
        test: {
          template: '<div><slot name="test"></slot> world</div>'
        }
      }
    }).$mount()
    expect(vm.$el.innerHTML).toBe('hello world')
  })

  it('combined with v-for', () => {
    const vm = new Vue({
      template: '<div><test v-for="i in 3" :key="i">{{ i }}</test></div>',
      components: {
        test: {
          template: '<div><slot></slot></div>'
        }
      }
    }).$mount()
    expect(vm.$el.innerHTML).toBe('<div>1</div><div>2</div><div>3</div>')
  })

  it('inside template v-if', () => {
    mount({
      childTemplate: `
        <div>
          <template v-if="true"><slot></slot></template>
        </div>
      `,
      parentContent: 'foo'
    })
    expect(child.$el.innerHTML).toBe('foo')
  })

  it('default slot should use fallback content if has only whitespace', () => {
    mount({
      childTemplate: `
        <div>
          <slot name="first"><p>first slot</p></slot>
          <slot><p>this is the default slot</p></slot>
          <slot name="second"><p>second named slot</p></slot>
        </div>
      `,
      parentContent: `<div slot="first">1</div> <div slot="second">2</div> <div slot="second">2+</div>`
    })
    expect(child.$el.innerHTML).toBe(
      '<div>1</div> <p>this is the default slot</p> <div>2</div><div>2+</div>'
    )
  })

  it('programmatic access to $slots', () => {
    const vm = new Vue({
      template: '<test><p slot="a">A</p><div>C</div><p slot="b">B</p></test>',
      components: {
        test: {
          render () {
            expect(this.$slots.a.length).toBe(1)
            expect(this.$slots.a[0].tag).toBe('p')
            expect(this.$slots.a[0].children.length).toBe(1)
            expect(this.$slots.a[0].children[0].text).toBe('A')

            expect(this.$slots.b.length).toBe(1)
            expect(this.$slots.b[0].tag).toBe('p')
            expect(this.$slots.b[0].children.length).toBe(1)
            expect(this.$slots.b[0].children[0].text).toBe('B')

            expect(this.$slots.default.length).toBe(1)
            expect(this.$slots.default[0].tag).toBe('div')
            expect(this.$slots.default[0].children.length).toBe(1)
            expect(this.$slots.default[0].children[0].text).toBe('C')

            return this.$slots.default[0]
          }
        }
      }
    }).$mount()
    expect(vm.$el.tagName).toBe('DIV')
    expect(vm.$el.textContent).toBe('C')
  })

  it('warn if user directly returns array', () => {
    new Vue({
      template: '<test><div slot="foo"></div><div slot="foo"></div></test>',
      components: {
        test: {
          render () {
            return this.$slots.foo
          }
        }
      }
    }).$mount()
    expect('Render function should return a single root node').toHaveBeenWarned()
  })

  // #3254
  it('should not keep slot name when passed further down', () => {
    const vm = new Vue({
      template: '<test><span slot="foo">foo</span></test>',
      components: {
        test: {
          template: '<child><slot name="foo"></slot></child>',
          components: {
            child: {
              template: `
                <div>
                  <div class="default"><slot></slot></div>
                  <div class="named"><slot name="foo"></slot></div>
                </div>
              `
            }
          }
        }
      }
    }).$mount()
    expect(vm.$el.querySelector('.default').textContent).toBe('foo')
    expect(vm.$el.querySelector('.named').textContent).toBe('')
  })

  it('should not keep slot name when passed further down (nested)', () => {
    const vm = new Vue({
      template: '<wrap><test><span slot="foo">foo</span></test></wrap>',
      components: {
        wrap: {
          template: '<div><slot></slot></div>'
        },
        test: {
          template: '<child><slot name="foo"></slot></child>',
          components: {
            child: {
              template: `
                <div>
                  <div class="default"><slot></slot></div>
                  <div class="named"><slot name="foo"></slot></div>
                </div>
              `
            }
          }
        }
      }
    }).$mount()
    expect(vm.$el.querySelector('.default').textContent).toBe('foo')
    expect(vm.$el.querySelector('.named').textContent).toBe('')
  })

  it('should not keep slot name when passed further down (functional)', () => {
    const child = {
      template: `
        <div>
          <div class="default"><slot></slot></div>
          <div class="named"><slot name="foo"></slot></div>
        </div>
      `
    }

    const vm = new Vue({
      template: '<test><span slot="foo">foo</span></test>',
      components: {
        test: {
          functional: true,
          render (h, ctx) {
            const slots = ctx.slots()
            return h(child, slots.foo)
          }
        }
      }
    }).$mount()
    expect(vm.$el.querySelector('.default').textContent).toBe('foo')
    expect(vm.$el.querySelector('.named').textContent).toBe('')
  })

  // #3400
  it('named slots should be consistent across re-renders', done => {
    const vm = new Vue({
      template: `
        <comp>
          <div slot="foo">foo</div>
        </comp>
      `,
      components: {
        comp: {
          data () {
            return { a: 1 }
          },
          template: `<div><slot name="foo"></slot>{{ a }}</div>`
        }
      }
    }).$mount()
    expect(vm.$el.textContent).toBe('foo1')
    vm.$children[0].a = 2
    waitForUpdate(() => {
      expect(vm.$el.textContent).toBe('foo2')
    }).then(done)
  })

  // #3437
  it('should correctly re-create components in slot', done => {
    const calls = []
    const vm = new Vue({
      template: `
        <comp ref="child">
          <div slot="foo">
            <child></child>
          </div>
        </comp>
      `,
      components: {
        comp: {
          data () {
            return { ok: true }
          },
          template: `<div><slot name="foo" v-if="ok"></slot></div>`
        },
        child: {
          template: '<div>child</div>',
          created () {
            calls.push(1)
          },
          destroyed () {
            calls.push(2)
          }
        }
      }
    }).$mount()

    expect(calls).toEqual([1])
    vm.$refs.child.ok = false
    waitForUpdate(() => {
      expect(calls).toEqual([1, 2])
      vm.$refs.child.ok = true
    }).then(() => {
      expect(calls).toEqual([1, 2, 1])
      vm.$refs.child.ok = false
    }).then(() => {
      expect(calls).toEqual([1, 2, 1, 2])
    }).then(done)
  })

  it('should support duplicate slots', done => {
    const vm = new Vue({
      template: `
        <foo ref="foo">
          <div slot="a">{{ n }}</div>
        </foo>
      `,
      data: {
        n: 1
      },
      components: {
        foo: {
          data() {
            return { ok: true }
          },
          template: `
            <div>
              <slot name="a" />
              <slot v-if="ok" name="a" />
              <pre><slot name="a" /></pre>
            </div>
          `
        }
      }
    }).$mount()
    expect(vm.$el.innerHTML).toBe(`<div>1</div> <div>1</div> <pre><div>1</div></pre>`)
    vm.n++
    waitForUpdate(() => {
      expect(vm.$el.innerHTML).toBe(`<div>2</div> <div>2</div> <pre><div>2</div></pre>`)
      vm.n++
    }).then(() => {
      expect(vm.$el.innerHTML).toBe(`<div>3</div> <div>3</div> <pre><div>3</div></pre>`)
      vm.$refs.foo.ok = false
    }).then(() => {
      expect(vm.$el.innerHTML).toBe(`<div>3</div> <!----> <pre><div>3</div></pre>`)
      vm.n++
      vm.$refs.foo.ok = true
    }).then(() => {
      expect(vm.$el.innerHTML).toBe(`<div>4</div> <div>4</div> <pre><div>4</div></pre>`)
    }).then(done)
  })

  // #3518
  it('events should not break when slot is toggled by v-if', done => {
    const spy = jasmine.createSpy()
    const vm = new Vue({
      template: `<test><div class="click" @click="test">hi</div></test>`,
      methods: {
        test: spy
      },
      components: {
        test: {
          data: () => ({
            toggle: true
          }),
          template: `<div v-if="toggle"><slot></slot></div>`
        }
      }
    }).$mount()

    document.body.appendChild(vm.$el)
    expect(vm.$el.textContent).toBe('hi')
    vm.$children[0].toggle = false
    waitForUpdate(() => {
      vm.$children[0].toggle = true
    }).then(() => {
      triggerEvent(vm.$el.querySelector('.click'), 'click')
      expect(spy).toHaveBeenCalled()
    }).then(() => {
      document.body.removeChild(vm.$el)
    }).then(done)
  })

  it('renders static tree with text', () => {
    const vm = new Vue({
      template: `<div><test><template><div></div>Hello<div></div></template></test></div>`,
      components: {
        test: {
          template: '<div><slot></slot></div>'
        }
      }
    })
    vm.$mount()
    expect('Error when rendering root').not.toHaveBeenWarned()
  })

  // #3872
  it('functional component as slot', () => {
    const vm = new Vue({
      template: `
        <parent>
          <child>one</child>
          <child slot="a">two</child>
        </parent>
      `,
      components: {
        parent: {
          template: `<div><slot name="a"></slot><slot></slot></div>`
        },
        child: {
          functional: true,
          render (h, { slots }) {
            return h('div', slots().default)
          }
        }
      }
    }).$mount()
    expect(vm.$el.innerHTML.trim()).toBe('<div>two</div><div>one</div>')
  })

  // #4209
  it('slot of multiple text nodes should not be infinitely merged', done => {
    const wrap = {
      template: `<inner ref="inner">foo<slot></slot></inner>`,
      components: {
        inner: {
          data: () => ({ a: 1 }),
          template: `<div>{{a}}<slot></slot></div>`
        }
      }
    }
    const vm = new Vue({
      template: `<wrap ref="wrap">bar</wrap>`,
      components: { wrap }
    }).$mount()

    expect(vm.$el.textContent).toBe('1foobar')
    vm.$refs.wrap.$refs.inner.a++
    waitForUpdate(() => {
      expect(vm.$el.textContent).toBe('2foobar')
    }).then(done)
  })

  // #4315
  it('functional component passing slot content to stateful child component', done => {
    const ComponentWithSlots = {
      render (h) {
        return h('div', this.$slots.slot1)
      }
    }

    const FunctionalComp = {
      functional: true,
      render (h) {
        return h(ComponentWithSlots, [h('span', { slot: 'slot1' }, 'foo')])
      }
    }

    const vm = new Vue({
      data: { n: 1 },
      render (h) {
        return h('div', [this.n, h(FunctionalComp)])
      }
    }).$mount()

    expect(vm.$el.textContent).toBe('1foo')
    vm.n++
    waitForUpdate(() => {
      // should not lose named slot
      expect(vm.$el.textContent).toBe('2foo')
    }).then(done)
  })

  it('the elements of slot should be updated correctly', done => {
    const vm = new Vue({
      data: { n: 1 },
      template: '<div><test><span v-for="i in n" :key="i">{{ i }}</span><input value="a"/></test></div>',
      components: {
        test: {
          template: '<div><slot></slot></div>'
        }
      }
    }).$mount()
    expect(vm.$el.innerHTML).toBe('<div><span>1</span><input value="a"></div>')
    const input = vm.$el.querySelector('input')
    input.value = 'b'
    vm.n++
    waitForUpdate(() => {
      expect(vm.$el.innerHTML).toBe('<div><span>1</span><span>2</span><input value="a"></div>')
      expect(vm.$el.querySelector('input')).toBe(input)
      expect(vm.$el.querySelector('input').value).toBe('b')
    }).then(done)
  })

  // GitHub issue #5888
  it('should resolve correctly slot with keep-alive', () => {
    const vm = new Vue({
      template: `
      <div>
        <container>
          <keep-alive slot="foo">
            <child></child>
          </keep-alive>
        </container>
      </div>
      `,
      components: {
        container: {
          template:
            '<div><slot>default</slot><slot name="foo">named</slot></div>'
        },
        child: {
          template: '<span>foo</span>'
        }
      }
    }).$mount()
    expect(vm.$el.innerHTML).toBe('<div>default<span>foo</span></div>')
  })

  // #6372, #6915
  it('should handle nested components in slots properly', done => {
    const TestComponent = {
      template: `
        <component :is="toggleEl ? 'b' : 'i'">
          <slot />
        </component>
      `,
      data () {
        return {
          toggleEl: true
        }
      }
    }

    const vm = new Vue({
      template: `
        <div>
          <test-component ref="test">
            <div>
              <foo/>
            </div>
            <bar>
              <foo/>
            </bar>
          </test-component>
        </div>
      `,
      components: {
        TestComponent,
        foo: {
          template: `<div>foo</div>`
        },
        bar: {
          template: `<div>bar<slot/></div>`
        }
      }
    }).$mount()

    expect(vm.$el.innerHTML).toBe(`<b><div><div>foo</div></div> <div>bar<div>foo</div></div></b>`)

    vm.$refs.test.toggleEl = false
    waitForUpdate(() => {
      expect(vm.$el.innerHTML).toBe(`<i><div><div>foo</div></div> <div>bar<div>foo</div></div></i>`)
    }).then(done)
  })

  it('should preserve slot attribute if not absorbed by a Vue component', () => {
    const vm = new Vue({
      template: `
        <div>
          <div slot="foo"></div>
        </div>
      `
    }).$mount()
    expect(vm.$el.children[0].getAttribute('slot')).toBe('foo')
  })

  it('passing a slot down as named slot', () => {
    const Bar = {
      template: `<div class="bar"><slot name="foo"/></div>`
    }

    const Foo = {
      components: { Bar },
      template: `<div class="foo"><bar><slot slot="foo"/></bar></div>`
    }

    const vm = new Vue({
      components: { Foo },
      template: `<div><foo>hello</foo></div>`
    }).$mount()

    expect(vm.$el.innerHTML).toBe('<div class="foo"><div class="bar">hello</div></div>')
  })

  it('fallback content for named template slot', () => {
    const Bar = {
      template: `<div class="bar"><slot name="foo">fallback</slot></div>`
    }

    const Foo = {
      components: { Bar },
      template: `<div class="foo"><bar><template slot="foo"/><slot/></template></bar></div>`
    }

    const vm = new Vue({
      components: { Foo },
      template: `<div><foo></foo></div>`
    }).$mount()

    expect(vm.$el.innerHTML).toBe('<div class="foo"><div class="bar">fallback</div></div>')
  })

  // #7106
  it('should not lose functional slot across renders', done => {
    const One = {
      data: () => ({
        foo: true
      }),
      render (h) {
        this.foo
        return h('div', this.$slots.slot)
      }
    }

    const Two = {
      render (h) {
        return h('span', this.$slots.slot)
      }
    }

    const Three = {
      functional: true,
      render: (h, { children }) => h('span', children)
    }

    const vm = new Vue({
      template: `
        <div>
          <one ref="one">
            <two slot="slot">
              <three slot="slot">hello</three>
            </two>
          </one>
        </div>
      `,
      components: { One, Two, Three }
    }).$mount()

    expect(vm.$el.textContent).toBe('hello')
    // trigger re-render of <one>
    vm.$refs.one.foo = false
    waitForUpdate(() => {
      // should still be there
      expect(vm.$el.textContent).toBe('hello')
    }).then(done)
  })

  it('should allow passing named slots as raw children down multiple layers of functional component', () => {
    const CompB = {
      functional: true,
      render (h, { slots }) {
        return slots().foo
      }
    }

    const CompA = {
      functional: true,
      render (h, { children }) {
        return h(CompB, children)
      }
    }

    const vm = new Vue({
      components: {
        CompA
      },
      template: `
        <div>
          <comp-a>
            <span slot="foo">foo</span>
          </comp-a>
        </div>
      `
    }).$mount()

    expect(vm.$el.textContent).toBe('foo')
  })

  // #7817
  it('should not match wrong named slot in functional component on re-render', done => {
    const Functional = {
      functional: true,
      render: (h, ctx) => ctx.slots().default
    }

    const Stateful = {
      data () {
        return { ok: true }
      },
      render (h) {
        this.ok // register dep
        return h('div', [
          h(Functional, this.$slots.named)
        ])
      }
    }

    const vm = new Vue({
      template: `<stateful ref="stateful"><div slot="named">foo</div></stateful>`,
      components: { Stateful }
    }).$mount()

    expect(vm.$el.textContent).toBe('foo')
    vm.$refs.stateful.ok = false
    waitForUpdate(() => {
      expect(vm.$el.textContent).toBe('foo')
    }).then(done)
  })

  // #7975
  it('should update named slot correctly when its position in the tree changed', done => {
    const ChildComponent = {
      template: '<b>{{ message }}</b>',
      props: ['message']
    }
     let parentVm
    const ParentComponent = {
      template: `
        <div>
          <span v-if="alter">
            <span><slot name="foo" /></span>
          </span>
          <span v-else>
            <slot name="foo" />
          </span>
        </div>
      `,
      data () {
        return {
          alter: true
        }
      },
      mounted () {
        parentVm = this
      }
    }
     const vm = new Vue({
      template: `
        <parent-component>
          <span slot="foo">
            <child-component :message="message" />
          </span>
        </parent-component>
      `,
      components: {
        ChildComponent,
        ParentComponent
      },
      data () {
        return {
          message: 1
        }
      }
    }).$mount()
     expect(vm.$el.firstChild.innerHTML).toBe('<span><span><b>1</b></span></span>')
    parentVm.alter = false
    waitForUpdate(() => {
      vm.message = 2
    }).then(() => {
      expect(vm.$el.firstChild.innerHTML).toBe('<span><b>2</b></span>')
    }).then(done)
  })
})