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Custom Mount Commands and Styles

When working in an app that's any more complex than a Hello World app, you'll want to create a custom Mount command if one wasn't created for you during the automatic configuration step.

If you're using a UI Library like Vuetify or Tailwind, you'll want to replicate the setup you're doing in your normal application for your components.

danger

Failure to replicate the environment completely may lead to:

  1. Your component not compiling at all.
  2. Partially broken functionality.
  3. Broken styles. (Icon fonts, etc)
  4. Error logs in the console.

Broken Stylesโ€‹

Because your component's styles are business logic, you need to make sure the styles are identical between your test and development environments.

If your component has Times New Roman font, if the spacing is off, or if your icon fonts aren't rendering, you'll need to investigate what the difference between the test and development environment is.

Missing Iconsโ€‹

Icons are generally installed in your main.js, css, or at the bundler level (e.g. Iconify and unplugin-icons).

Ensure that your Icons are being installed in your support file just like they are in your main.js file OR as they are in your index.html file.

Times New Roman Fontsโ€‹

Make sure you've added any page-level loaded fonts into the HTML fixture!

Additionally, make sure that any page-level styles are not dependent on component hierarchy, but are instead extracted into a main.css (or scss) file and imported at the top of your support file.

cypress/support/component.js
// Should import normalize.css, etc
// The top of this supportfile should look very similar
// to your main.js
import '../../src/main.css'

Replicating the HTML fixturesโ€‹

Sometimes, you'll have a third-party plugin, like a tooltip, modal, or other portal-style component that wants to bind to a DOM node outside of your app's normal component hierarchy.

At any given time, or in a future refactor, your component under test may decide it wants to use that library, so you should make sure the HTML you're using to fixture your component sandbox is identical to that of the page you'll be rendering the component in.

If you always make sure your production HTML fixtures are close to your test HTML fixtures, you'll rarely have to modify your tests when you refactor the implementation of the component.

Editing your HTML fixtureโ€‹

To edit the spec's fixtured HTML, open up the cypress/support/component-index.html file that was fixtured for you during automatic configuration.

Anything you change in this file will show up automatically in your tests.

You may also want to load custom libraries like jquery or tailwind like this -- if that's how you load those libraries when your application is shipped to production.

Custom Mount Commandsโ€‹

If you used the automatic configuration option to setup your app, you'll have the global cy.mount() Cypress Command available throughout your tests.

As your application grows past the proof-of-concept stage, you'll want to use plugins and tools like Vue Router, Vuex, Pinia, or Vue I18n. These are plugins that are usually installed in your application's entry point file (main.js usually). You may also pull in global plugins or style resets like normalize.css

Replicating Pluginsโ€‹

Most applications will have state management or routing. Both of these are Vue plugins.

import { createPinia } from 'pinia' // or Vuex
import { createI18n } from 'vue-i18n'
import { mount } from 'cypress/vue'
import { h } from 'vue'

// We recommend that you pull this out
// into a constants file that you share with
// your main.js file.
const i18nOptions = {
  locale: 'en',
  messages: {
    en: {
      hello: 'hello!',
    },
    ja: {
      hello: 'ใ“ใ‚“ใซใกใฏ๏ผ',
    },
  },
}

Cypress.Commands.add('mount', (component, ...args) => {
  args.global = args.global || {}
  args.global.plugins = args.global.plugins || []
  args.global.plugins.push(createPinia())
  args.global.plugins.push(createI18n())

  return mount(() => {
    return h(VApp, {}, component)
  }, ...args)
})

Replicating the expected Component Hierarchyโ€‹

Some Vue applications, most famously Vue apps built on top of Vuetify, require certain components to be structured in a specific hierarchy.

All Vuetify applications require that you wrap your app in a VApp component when you build it. This is an implementation detail of Vuetify, but once users try to test components that depend on Vuetify, they get Vuetify-specific compilation errors and quickly find out that they need to replicate that component hierarchy any time they need to mount a component that uses a Vuetify component!

Custom cy.mount() commands to the rescue! You may find the JSX syntax to be more straightforward.

You'll also need to replicate the plugin setup steps from the Vuetify docs for everything to compile.

import Vuetify from 'vuetify/lib'
import { VApp } from 'vuetify'
import { mount } from 'cypress/vue'
import { h } from 'vue'

// We recommend that you pull this out
// into a constants file that you share with
// your main.js file.
const vuetifyOptions = {}

Cypress.Commands.add('mount', (component, ...args) => {
  args.global = args.global || {}
  args.global.plugins = args.global.plugins || []
  args.global.plugins.push(new Vuetify(vuetifyOptions))

  return mount(() => {
    return h(VApp, {}, component)
  }, ...args)
})

At this point, you should be able to setup a complex application and mount components that use all of Vue's language features.

Congrats! Happy building. ๐ŸŽ‰

Vue Routerโ€‹

To use Vue Router, create a command to register the plugin and pass in a custom implementation of the router via the options param:

import { mount } from 'cypress/vue'
import { createMemoryHistory, createRouter } from 'vue-router'
import { routes } from '../../src/router'

Cypress.Commands.add('mount', (component, options = {}) => {
  // Setup options object
  options.global = options.global || {}
  options.global.plugins = options.global.plugins || []

  // create router if one is not provided
  if (!options.router) {
    options.router = createRouter({
      routes: routes,
      history: createMemoryHistory(),
    })
  }

  // Add router plugin
  options.global.plugins.push({
    install(app) {
      app.use(options.router)
    },
  })

  return mount(component, options)
})
import { mount } from 'cypress/vue'
import { Router } from 'vue-router'

type MountParams = Parameters<typeof mount>
type OptionsParam = MountParams[1] & { router?: Router }

declare global {
  namespace Cypress {
    interface Chainable {
      /**
       * Helper mount function for Vue Components
       * @param component Vue Component or JSX Element to mount
       * @param options Options passed to Vue Test Utils
       */
      mount(component: any, options?: OptionsParam): Chainable<any>
    }
  }
}

Usage:

Calling router.push() in the router for Vue 3 is an asynchronous operation. Use the cy.wrap command to have Cypress await the promise's resolve before it continues with other commands:

import Navigation from './Navigation.vue'
import { routes } from '../router'
import { createMemoryHistory, createRouter } from 'vue-router'

it('home link should be active when url is "/"', () => {
  // No need to pass in custom router as default url is '/'
  cy.mount(<Navigation />)

  cy.get('a').contains('Home').should('have.class', 'router-link-active')
})

it('login link should be active when url is "/login"', () => {
  // Create a new router instance for each test
  const router = createRouter({
    routes: routes,
    history: createMemoryHistory(),
  })

  // Change location to `/login`,
  // and await on the promise with cy.wrap
  cy.wrap(router.push('/login'))

  // Pass the already initialized router for use
  cy.mount(<Navigation />, { router })

  cy.get('a').contains('Login').should('have.class', 'router-link-active')
})

Vuexโ€‹

To use a component that uses Vuex, create a mount command that configures a Vuex store for your component:

import { mount } from 'cypress/vue'
import { getStore } from '../../src/plugins/store'

Cypress.Commands.add('mount', (component, options = {}) => {
  // Setup options object
  options.global = options.global || {}
  options.global.stubs = options.global.stubs || {}
  options.global.stubs['transition'] = false
  options.global.components = options.global.components || {}
  options.global.plugins = options.global.plugins || []

  // Use store passed in from options, or initialize a new one
  const { store = getStore(), ...mountOptions } = options

  // Add Vuex plugin
  options.global.plugins.push({
    install(app) {
      app.use(store)
    },
  })

  return mount(component, mountOptions)
})
info

The getStore method is a factory method that initializes Vuex and creates a new store. It is important that the store be initialized with each new test to ensure changes to the store don't affect other tests.

TypeScript Typings
import { mount } from 'cypress/vue'
import { Store } from 'vuex'

type MountParams = Parameters<typeof mount>
type OptionsParam = MountParams[1]

declare global {
  namespace Cypress {
    interface Chainable {
      /**
       * Helper mount function for Vue Components
       * @param component Vue Component or JSX Element to mount
       * @param options Options passed to Vue Test Utils
       */
      mount(
        component: any,
        options?: OptionsParam & { store?: Store }
      ): Chainable<any>
    }
  }
}
Usage
import { getStore } from '@/plugins/store'
import UserProfile from './UserProfile.vue'

it.only('User profile should display user name', () => {
  const user = { name: 'test person' }

  // getStore is a factory method that creates a new store
  const store = getStore()

  // mutate the store with user
  store.commit('setUser', user)

  cy.mount(UserProfile, {
    store,
  })

  cy.get('div.name').should('have.text', user.name)
})

Global Componentsโ€‹

If you have components that are registered globally in the main application file, set them up in your mount command so your component will render them properly:

import { mount } from 'cypress/vue'
import Button from '../../src/components/Button.vue'

Cypress.Commands.add('mount', (component, options = {}) => {
  // Setup options object
  options.extensions = options.extensions || {}
  options.extensions.plugins = options.extensions.plugins || []
  options.extensions.components = options.extensions.components || {}

  // Register global components
  options.extensions.components['Button'] = Button

  return mount(component, options)
})