Requested resource not found

Sometimes you use cy.request to get a resource that might not exist. The server returns 404 and the command fails. In this recipe, I show how to deal with this error by abstracting it away in an utility function. You can read this recipe or watch the video "Return Cypress Chain".

First, let's look at an incorrect solution.

// 🚨 INCORRECT, this will NOT WORK, just for DEMO
function getTodo(id) {
  const serverUrl = 'https://jsonplaceholder.cypress.io'
  cy.request(`${serverUrl}/todos/${id}`).its('body')
  // if the Todo is not found, return an error
  return 'Todo not found'
}
getTodo(1)

The above function getTodo schedules the cy.request command to run by adding it to the Cypress command queue. The getTodo also returns a string right away - probably not something you expect. Instead you want to return the Cypress command to let you attach more commands and assertions.

// 🚨 SLIGHTLY BETTER solution
// DOES NOT HANDLE 404 responses
function getTodo(id) {
  const serverUrl = 'https://jsonplaceholder.cypress.io'
  return cy.request(`${serverUrl}/todos/${id}`).its('body')
  // Hmm, we will never get here. How do we handle
  // a response from the server "Todo not found"?
  return 'Todo not found'
}
// getTodos now returns a Cypress command, so we can validate
// the value it yields when the request completes
getTodo(1)
  .should('deep.include', {
    // we know only some properties from the object
    id: 1,
    userId: 1,
  })
  // continue working with the yielded Todo object
  .its('title')
  .should('be.a', 'string')

The above approach is slightly better. Now let's add handling of 404 response.

// ✅ Good utility function
// that handles 404 responses and yields the object
function getTodo(id) {
  const serverUrl = 'https://jsonplaceholder.cypress.io'
  return cy
    .request({
      url: `${serverUrl}/todos/${id}`,
      failOnStatusCode: false,
    })
    .then((response) => {
      if (response.status === 404) {
        return 'Todo not found'
      }
      return response.body
    })
}
getTodo(1)
  .should('deep.include', {
    // we know only some properties from the object
    id: 1,
    userId: 1,
  })
  // continue working with the yielded Todo object
  .its('title')
  .should('be.a', 'string')
// asking for resource that does not exist
getTodo('does-not-exist').should('equal', 'Todo not found')

Bonus: compare two responses

Let's get two Todo items and check their responses to confirm they are the same. You can nest cy.then callbacks to get both objects before comparing them.

getTodo(20).then((first) => {
  getTodo(10 + 10).then((second) => {
    expect(first, 'todos are equal').to.deep.equal(second)
  })
})

We can also save the first response under an alias and use function () {...} callback to be able to access the first response using this.<alias>:

getTodo(20)
  .as('first')
  .then(function () {
    // by using "function () {...}" callback
    // we get access to the test context object via "this"
    // that's where every alias created using cy.as command
    // is available as a property
    getTodo(10 + 10).should('deep.equal', this.first)
  })