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').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

[alexsch01]

Does Cypress' validation of cy.task function calls happen at runtime? Or is it type-checked internally?

[cursor]

Bug: Cypress Type Definitions Fail with Custom Config Paths

The hardcoded import path ../../../cypress.config in cli/types/cypress.d.ts is brittle. It assumes a specific, non-universal project structure where the user's cypress.config file is exactly three directories up from the types file (located within the Cypress package in node_modules). It also assumes the config file exports a CypressTasks property. This will cause TypeScript compilation errors for most Cypress installations, breaking the new type-safe cy.task functionality.

cli/types/cypress.d.ts#L5-L6

cypress/cli/types/cypress.d.ts

Lines 5 to 6 in 40c99ed

	type AllTasks = typeof import('../../../cypress.config')['CypressTasks']

Fix in Cursor • Fix in Web

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