задача

cy.task(event)
cy.task(event, arg)
cy.task(event, arg, options)

// in test
cy.task('log', 'This will be output to the terminal')

// in plugins file
module.exports = (on, config) => {
  on('task', {
    log(message) {
      console.log(message)

      return null
    },
  })
}

// in test
cy.task('hello', { greeting: 'Hello', name: 'World' })

// in plugins/index.js
module.exports = (on, config) => {
  on('task', {
    // deconstruct the individual properties
    hello({ greeting, name }) {
      console.log('%s, %s', greeting, name)

      return null
    },
  })
}

// in test
cy.task('readFileMaybe', 'my-file.txt').then((textOrNull) => { ... })

// in plugins/index.js
const fs = require('fs')

module.exports = (on, config) => {
  on('task', {
    readFileMaybe(filename) {
      if (fs.existsSync(filename)) {
        return fs.readFileSync(filename, 'utf8')
      }

      return null
    },
  })
}

// in test
cy.task('countFiles', 'cypress/downloads').then((count) => { ... })

// in plugins/index.js
const fs = require('fs')

module.exports = (on, config) => {
  on('task', {
    countFiles(folderName) {
      return new Promise((resolve, reject) => {
        fs.readdir(folderName, (err, files) => {
          if (err) {
            return reject(err)
          }

          resolve(files.length)
        })
      })
    },
  })
}

// in test
describe('e2e', () => {
  beforeEach(() => {
    cy.task('defaults:db')
    cy.visit('/')
  })

  it('displays article values', () => {
    cy.get('.article-list').should('have.length', 10)
  })
})

// in plugins/index.js
// we require some code in our app that
// is responsible for seeding our database
const db = require('../../server/src/db')

module.exports = (on, config) => {
  on('task', {
    'defaults:db': () => {
      return db.seed('defaults')
    },
  })
}

// in test
cy.task('pause', 1000)

// in plugins/index.js
module.exports = (on, config) => {
  on('task', {
    pause(ms) {
      return new Promise((resolve) => {
        // tasks should not resolve with undefined
        setTimeout(() => resolve(null), ms)
      })
    },
  })
}

// in test
describe('Href visit', () => {
  it('captures href', () => {
    cy.visit('https://www.mywebapp.com')
    cy.get('a')
      .invoke('attr', 'href')
      .then((href) => {
        // href is not same-origin as current url
        // like https://www.anotherwebapp.com
        cy.task('setHref', href)
      })
  })

  it('visit href', () => {
    cy.task('getHref').then((href) => {
      // visit non same-origin url https://www.anotherwebapp.com
      cy.visit(href)
    })
  })
})

// in plugins/index.js
let href

module.exports = (on, config) => {
  on('task', {
    setHref: (val) => {
      return (href = val)
    },
    getHref: () => {
      return href
    },
  })
}

// will fail if seeding the database takes longer than 20 seconds to finish
cy.task('seedDatabase', null, { timeout: 20000 })

// in plugins/index.js file
const skipAndOnlyTask = require('cypress-skip-and-only-ui/task')
const fs = require('fs')
const myTask = {
  readFileMaybe(filename) {
    if (fs.existsSync(filename)) {
      return fs.readFileSync(filename, 'utf8')
    }

    return null
  },
}

// register plugin's task
on('task', skipAndOnlyTask)
// and register my own task
on('task', myTask)

Cypress.config('taskTimeout', 30000)
Cypress.config('taskTimeout') // => 30000

describe('has data available from database', { taskTimeout: 90000 }, () => {
  before(() => {
    cy.task('seedDatabase')
  })

  // tests

  after(() => {
    cy.task('resetDatabase')
  })
})

// in test
const dbName = 'stagingA'
const query = 'SELECT * FROM users'

cy.task('queryDatabase', { dbName, query })

// in plugins/index.js
const mysql = require('mysql')
// the connection strings for different databases could
// come from a config file, or from environment variables
const connections = {
  stagingA: {
    host: 'staging.my.co',
    user: 'test',
    password: '***',
    database: 'users',
  },
  stagingB: {
    host: 'staging-b.my.co',
    user: 'test',
    password: '***',
    database: 'users',
  },
}

// querying the database from Node
function queryDB(connectionInfo, query) {
  const connection = mysql.createConnection(connectionInfo)

  connection.connect()

  return new Promise((resolve, reject) => {
    connection.query(query, (error, results) => {
      if (error) {
        return reject(error)
      }

      connection.end()

      return resolve(results)
    })
  })
}
module.exports = (on, config) => {
  on('task', {
    // destructure the argument into the individual fields
    queryDatabase({ dbName, query }) {
      const connectionInfo = connections[dbName]

      if (!connectionInfo) {
        throw new Error(`Do not have DB connection under name ${dbName}`)
      }

      return queryDB(connectionInfo, query)
    },
  })
}

// in test
cy.task('date', new Date()).then((s) => {
  // the yielded result is a string
  // we need to convert it to Date object
  const result = new Date(s)
})

// in plugins/index.js
module.exports = (on, config) => {
  on('task', {
    date(s) {
      // s is a string, so convert it to Date
      const d = new Date(s)

      // do something with the date
      // and return it back
      return d
    },
  })
}

cy.task('readJson', 'cypress.json')