Is "Intercept" ensuring that the request is not sent to the server?

Question

Is it possible in Cypress to send a request that won't reach the server but instead return a chosen response to us? I consider cy.intercept(), but does this function intercept the request that was sent to the server, along with the response from the server, which can then be modified?

Answer 1

Yes, there are various hooks that can be used for this purpose.

In the following example I use the before:response to make a modification to the response.

To explore the way the hooks work, I use a win.fetch(...) which creates the request independently of the application under test.

cy.intercept('/todos/*', (req) => {
  req.on('before:response', (res) => {

    // take a look at the actual server response
    console.log('before:response', res.body)  

    // make a modification to that response
    res.body.title = 'modified in before:response'
  })
})
.as('todos')

// make a dummy call to your API to check the intercept is functional
cy.window().then(win => win.fetch('https://jsonplaceholder.typicode.com/todos/1'))


cy.wait('@todos')
  .then(({request, response}) => {

    // take a look at the modified server response
    console.log('wait', response.body)

    // should contain the changed data
    expect(response.body.title).to.eq('modified in before:response')
  })

You can see res modified tag in the Cypress log