Testing Key, Mouse and other DOM events

Learn to traverse and interact with the DOM with a free lesson on Vue School

Trigger events

The Wrapper exposes an async trigger method. It can be used to trigger DOM events.

test('triggers a click', async () => {
  const wrapper = mount(MyComponent)

  await wrapper.trigger('click')
})

You should be aware that the find method returns a Wrapper as well. Assuming MyComponent contains a button, the following code clicks the button.

test('triggers a click', async () => {
  const wrapper = mount(MyComponent)

  await wrapper.find('button').trigger('click')
})

Options

The trigger method takes an optional options object. The properties in the options object are added to the Event.

Note that target cannot be added in the options object.

test('triggers a click', async () => {
  const wrapper = mount(MyComponent)

  await wrapper.trigger('click', { button: 0 })
})

Mouse Click Example

Component under test

<template>
  <div>
    <button class="yes" @click="callYes">Yes</button>
    <button class="no" @click="callNo">No</button>
  </div>
</template>

<script>
  export default {
    name: 'YesNoComponent',

    props: {
      callMe: {
        type: Function
      }
    },

    methods: {
      callYes() {
        this.callMe('yes')
      },
      callNo() {
        this.callMe('no')
      }
    }
  }
</script>

Test

import YesNoComponent from '@/components/YesNoComponent'
import { mount } from '@vue/test-utils'
import sinon from 'sinon'

it('Click on yes button calls our method with argument "yes"', async () => {
  const spy = sinon.spy()
  const wrapper = mount(YesNoComponent, {
    propsData: {
      callMe: spy
    }
  })
  await wrapper.find('button.yes').trigger('click')

  spy.should.have.been.calledWith('yes')
})

Keyboard Example

Component under test

This component allows to increment/decrement the quantity using various keys.

<template>
  <input type="text" @keydown.prevent="onKeydown" v-model="quantity" />
</template>

<script>
  const KEY_DOWN = 40
  const KEY_UP = 38
  const ESCAPE = 27

  export default {
    data() {
      return {
        quantity: 0
      }
    },

    methods: {
      increment() {
        this.quantity += 1
      },
      decrement() {
        this.quantity -= 1
      },
      clear() {
        this.quantity = 0
      },
      onKeydown(e) {
        if (e.keyCode === ESCAPE) {
          this.clear()
        }
        if (e.keyCode === KEY_DOWN) {
          this.decrement()
        }
        if (e.keyCode === KEY_UP) {
          this.increment()
        }
        if (e.key === 'a') {
          this.quantity = 13
        }
      }
    },

    watch: {
      quantity: function (newValue) {
        this.$emit('input', newValue)
      }
    }
  }
</script>

Test

import QuantityComponent from '@/components/QuantityComponent'
import { mount } from '@vue/test-utils'

describe('Key event tests', () => {
  it('Quantity is zero by default', () => {
    const wrapper = mount(QuantityComponent)
    expect(wrapper.vm.quantity).toBe(0)
  })

  it('Up arrow key increments quantity by 1', async () => {
    const wrapper = mount(QuantityComponent)
    await wrapper.trigger('keydown.up')
    expect(wrapper.vm.quantity).toBe(1)
  })

  it('Down arrow key decrements quantity by 1', async () => {
    const wrapper = mount(QuantityComponent)
    wrapper.vm.quantity = 5
    await wrapper.trigger('keydown.down')
    expect(wrapper.vm.quantity).toBe(4)
  })

  it('Escape sets quantity to 0', async () => {
    const wrapper = mount(QuantityComponent)
    wrapper.vm.quantity = 5
    await wrapper.trigger('keydown.esc')
    expect(wrapper.vm.quantity).toBe(0)
  })

  it('Magic character "a" sets quantity to 13', async () => {
    const wrapper = mount(QuantityComponent)
    await wrapper.trigger('keydown', {
      key: 'a'
    })
    expect(wrapper.vm.quantity).toBe(13)
  })
})

Limitations

A key name after the dot keydown.up is translated to a keyCode. This is supported for the following names:

key name	key code
enter	13
esc	27
tab	9
space	32
delete	46
backspace	8
insert	45
up	38
down	40
left	37
right	39
end	35
home	36
pageup	33
pagedown	34