Cypress : How to get returned value from custom commands ? (Cypress-promise)

Question

I'm searching a way to get back a return value returned by a custom Cypress commands.

I'm currently using Cypress and Cypress-promise lib (https://www.npmjs.com/package/cypress-promise)

Currently, result is that: log1=CAR 1 log2=null

Where is my mistake ?

Test file:

it('Test 1', async function() {      const carName = await promisify(cy.set_typeCarName());      cy.log("log2 = " + carName ); }); 

module:

set_typeCarName() {      let carName = "CAR 1";      cy.get('#newSiteCityInput').type(carName);      cy.log("log1 = " + carName);      return carName; };  Cypress.Commands.add('set_typeCarName',() => {     webnewsite.set_typeCarName(); }); 

Answer 1

To do this I'm using wrap() to return a Chainable containing the value I want to return.

Module

function foo() {   return cy.wrap('foo'); }  Cypress.Commands.add('foo', foo); 

Test File

cy.foo().then(value => console.log(value)); // foo 

Since wrap() is returning a Cypress.Chainable, we can call .then() on our commands. What ever is passed into wrap() is yielded to the next command.

See also: Cypress wrap() documentation

Answer 2

Cypress introduces a new way of writing code instead of returning values, i.e. using alias. https://docs.cypress.io/guides/core-concepts/variables-and-aliases.html#Closures

Normal way of writing code

async function compute(){ const value = await (asynchronous function); return value; }  const x = await compute(); // #a console.log(x);            // #b 

How to do this is in Cypress, since we cannot use async/await in cypress

function() compute{   cy.get('p#text').then(p => {     const text = p.textContent;     cy.wrap(text).as('pText');     //even if we return text from here, it will not be accessible anywhere    }); }  compute();    // #a cy.get('@pText').then(text => {   console.log(text);  // #b } 

The crux is to alias the value and then use it in the next command

because

Cypress first runs through whole code and puts commands in queue
once code is in queue, next command in queue will only run after all callbacks of current command are completed, thus we can use above code pattern.