Trouble with updating a variable within a loop in Cypress

Question

Trouble with updating a variable within a loop in Cypress

During my experience with writing Cypress tests, I came across an issue that is preventing me from updating a specific variable. The goal of my test is to run a loop and update the questionId variable within each iteration for making API queries. However, the problem lies in the fact that the variable retains its initial value of 0 and fails to update while inside the loop. Despite researching various articles on Cypress' async/sync behavior, I have not been able to find a solution.

Below is a snippet of the test:

it('Should pass', function () {
            cy.visit(`${Cypress.env('appUrl')}/url`)
        
            let questionId: number = 0
            for (let index = 0; index < 9; index++) {
                cy.intercept({ method: 'GET', path: `${questionId}` }).as('questionData')
    
                    cy.log('next question id: ' + questionId)
    
                    cy.intercept({ method: 'POST', path: 'answers' }).as('answers')
                    cy.contains('button', 'Submit answer').click()
    
                    cy.wait('@answers')
                        .then((xhr: any) => {
                            expect(xhr.response.statusCode).to.eq(200)
    
                            questionId = xhr.response.body.data.next_question_id
                            cy.log('new question id: ' + questionId)
                            cy.contains('span', 'You are correct!').should('be.visible')
                            cy.contains('button', 'view solution').click()
                            cy.contains('button', 'continue').click()
                        })
            }
    
        })

javascript typescript iteration cypress

Answer 1

Answer №1

When working with Cypress, it can exhibit peculiar behavior when using traditional for loops. A better alternative is to utilize Cypress lodash's times function. (You can refer to an article on Lodash's times function, as Cypress._ is essentially a wrapper around Lodash.)

...
let questionId = 0;
Cypress._.times(9, () => {
  cy.intercept({ method: 'GET', path: `${questionId}` }).as('questionData')
    
  cy.log('next question id: ' + questionId)
    
  cy.intercept({ method: 'POST', path: 'answers' }).as('answers')
  cy.contains('button', 'Submit answer').click()
    
  cy.wait('@answers')
    .then((xhr: any) => {
       expect(xhr.response.statusCode).to.eq(200)
    
        questionId = xhr.response.body.data.next_question_id
        cy.log('new question id: ' + questionId)
        cy.contains('span', 'You are correct!').should('be.visible')
        cy.contains('button', 'view solution').click()
        cy.contains('button', 'continue').click()
  })
});

Answer 2

When working with Cypress, it can exhibit peculiar behavior when using traditional for loops. A better alternative is to utilize Cypress lodash's times function. (You can refer to an article on Lodash's times function, as Cypress._ is essentially a wrapper around Lodash.)

...
let questionId = 0;
Cypress._.times(9, () => {
  cy.intercept({ method: 'GET', path: `${questionId}` }).as('questionData')
    
  cy.log('next question id: ' + questionId)
    
  cy.intercept({ method: 'POST', path: 'answers' }).as('answers')
  cy.contains('button', 'Submit answer').click()
    
  cy.wait('@answers')
    .then((xhr: any) => {
       expect(xhr.response.statusCode).to.eq(200)
    
        questionId = xhr.response.body.data.next_question_id
        cy.log('new question id: ' + questionId)
        cy.contains('span', 'You are correct!').should('be.visible')
        cy.contains('button', 'view solution').click()
        cy.contains('button', 'continue').click()
  })
});

Answer 3

Answer №2

The issue lies in synchronous loops such as

for (let index = 0; index < 9; index++) {...}

which must finish executing before any Cypress commands can begin.

A similar constraint applies to

Cypress._.times(9, () => {...})

.

To address this, one solution is implementing a recursive function.

This approach ensures that asynchronous operations complete at each stage before advancing to the next step (this sequence is crucial as subsequent steps depend on previous outcomes)

const handleQuestion = (questionId, iteration=0) => {

  if (iteration === 9) return    // finished, exit

  cy.intercept({ method: 'GET', path: `${questionId}` }).as('questionData')
  // What is the purpose of the above intercept? 
  // Is it necessary to wait for it, and what triggers the GET?
  

  cy.log('next question id: ' + questionId)
  cy.intercept({ method: 'POST', path: 'answers' }).as('answers')
  cy.contains('button', 'Submit answer').click()
    
  cy.wait('@answers').then((xhr: any) => {
    expect(xhr.response.statusCode).to.eq(200)
    const nextQuestionId = xhr.response.body.data.next_question_id
    cy.log('new question id: ' + nextQuestionId)
    cy.contains('span', 'You are correct!').should('be.visible')
    cy.contains('button', 'view solution').click()
    cy.contains('button', 'continue').click()
      .then(() => {
        cy.contains('button', 'Submit answer')    // Ensure submit button
          .should('be.visible')                   // is ready for next question
          .and('be.enabled')
        handleQuestion(nextQuestionId, ++iteration)  // Proceed to next question
      })
  })
}

handleQuestion(0)  // Begin with question #0

The validation prior to the next iteration may require adjustments

cy.contains('button', 'Submit answer')    
  .should('be.visible')                   
  .and('be.enabled')

This segment is designed to await the readiness of the page for the forthcoming question.

You might also verify certain text indicating the prepared state like

cy.contains('Please submit your answer')

Answer 4

The issue lies in synchronous loops such as

for (let index = 0; index < 9; index++) {...}

which must finish executing before any Cypress commands can begin.

A similar constraint applies to

Cypress._.times(9, () => {...})

.

To address this, one solution is implementing a recursive function.

This approach ensures that asynchronous operations complete at each stage before advancing to the next step (this sequence is crucial as subsequent steps depend on previous outcomes)

const handleQuestion = (questionId, iteration=0) => {

  if (iteration === 9) return    // finished, exit

  cy.intercept({ method: 'GET', path: `${questionId}` }).as('questionData')
  // What is the purpose of the above intercept? 
  // Is it necessary to wait for it, and what triggers the GET?
  

  cy.log('next question id: ' + questionId)
  cy.intercept({ method: 'POST', path: 'answers' }).as('answers')
  cy.contains('button', 'Submit answer').click()
    
  cy.wait('@answers').then((xhr: any) => {
    expect(xhr.response.statusCode).to.eq(200)
    const nextQuestionId = xhr.response.body.data.next_question_id
    cy.log('new question id: ' + nextQuestionId)
    cy.contains('span', 'You are correct!').should('be.visible')
    cy.contains('button', 'view solution').click()
    cy.contains('button', 'continue').click()
      .then(() => {
        cy.contains('button', 'Submit answer')    // Ensure submit button
          .should('be.visible')                   // is ready for next question
          .and('be.enabled')
        handleQuestion(nextQuestionId, ++iteration)  // Proceed to next question
      })
  })
}

handleQuestion(0)  // Begin with question #0

The validation prior to the next iteration may require adjustments

cy.contains('button', 'Submit answer')    
  .should('be.visible')                   
  .and('be.enabled')

This segment is designed to await the readiness of the page for the forthcoming question.

You might also verify certain text indicating the prepared state like

cy.contains('Please submit your answer')

Trouble with updating a variable within a loop in Cypress

Answer №1

Answer №2

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