PROPOSAL: type-safe cy.task function

[alexsch01]

THIS IS A PROPOSAL

adds type-safety and autocomplete to cy.task function

---

cypress.config.js

const { defineConfig } = require('cypress')
const CypressTasks = require('./tasks')

const CypressConfig = defineConfig({
  e2e: {
    supportFile: false,
    setupNodeEvents(on, config) {
      on('task', CypressTasks)
    },
  },
})

module.exports = {
  ...CypressConfig,
  CypressTasks,
}

---

tasks.js

module.exports = {
  log(args) {
    console.log(args)
    return null;
  },

  /**
   * @param {any[]} args
   */
  logMany(args) {
    console.log(...args)
    return null;
  },

  getData() {
    return {
      response: {
        body: 'OK',
        status: 200,
      }
    }
  },

  /**
   * @param {string} x 
   * @returns {Promise<string>}
   */
  getSelf(x) {
    return new Promise((resolve) => {
      setTimeout(() => {
        resolve(x);
      }, 5000);
    });
  },
}

---

cypress/e2e/spec.cy.js

it('Example of cy.task', () => {
  cy.task('logMany', [1, 2, 3, null, 5])

  cy.task('getData', undefined).then(data => {
    expect(data.response.status).to.eq(200)
    expect(data.response.body).to.eq('OK')
  })

  cy.task('getSelf', "=========").then((x) => {
    cy.task('log', x)
  })
})

---

jsconfig.json

{
  "compilerOptions": {
    "types": ["cypress"],
    "checkJs": true,
    "lib": ["ES2021", "DOM"],
    "module": "preserve",
    "strictNullChecks": true,
  },
  "exclude": ["node_modules"]
}

---

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[alexsch01]

@jennifer-shehane this PR draft adds type-safety to cy.task calls

Autocomplete works and will have a type error in VSCode when the types mismatch (input/output) or when the cy.task method is the wrong name

I don't know of a better way of reading from the Cypress Config File since this only has to do with the code editor types side

Please let me know what the team thinks about this feature