server

Start a server to begin routing responses to cy.route() and to change the behavior of network requests.

Syntax

cy.server()
cy.server(options)

Usage

Correct Usage

cy.server()

Arguments

options (Object)

Pass in an options object to change the default behavior of cy.server(). These options are used for 2 different purposes:

• As defaults that are merged into cy.route().
• As configuration behavior for all requests.

The following options are merged in as default options to cy.route()

The following options control the behavior of the server affecting all requests

Yields

• cy.server() yields null .
• cy.server() cannot be chained further.

Examples

No Args

After starting a server:

• Any request that does NOT match a cy.route() will pass through to the server.
• Any request that matches the options.ignore function will NOT be logged or stubbed.
• You will see requests named as (XHR Stub) or (XHR) in the Command Log.

cy.server()

Options

Change defaults for cy.route()

By default cy.route() inherits some of its options from cy.server().

In this example, our matching requests will be delayed 1000ms and have a status of 422, but its response will be what was set in cy.route().

cy.server({
  method: 'POST',
  delay: 1000,
  status: 422,
  response: {},
})

cy.route('/users/', { errors: 'Name cannot be blank' })

Change the default delay for all routes

Adding delay can help simulate real world network latency. Normally stubbed responses return in under 20ms. Adding a delay can help you visualize how your application's state reacts to requests that are in flight.

// delay each route's response 1500ms
cy.server({ delay: 1500 })

Send 404s on unmatched requests

If you'd like Cypress to automatically send requests that do NOT match routes the following response:

Set force404 to true.

cy.server({ force404: true })
cy.route('/activities/**', 'fixture:activities.json')

// Application Code
$(() => {
  $.get('/activities')

  // this will be sent back 404 since it
  // does not match any of the cy.routes
  $.getJSON('/users.json')
})

Change the default response headers for all routes

When you stub requests, you can automatically control their response headers. This is useful when you want to send back meta data in the headers, such as pagination or token information.

cy.server({
  headers: {
    'x-token': 'abc-123-foo-bar',
  },
})

cy.route('GET', '/users/1', { id: 1, name: 'Amanda' }).as('getUser')
cy.visit('/users/1/profile')
cy.wait('@getUser')
  .its('responseHeaders')
  .should('have.property', 'x-token', 'abc-123-foo-bar') // true

// Application Code

// lets use the native XHR object
const xhr = new XMLHttpRequest()

xhr.open('GET', '/users/1')

xhr.onload = function () {
  const token = this.getResponseHeader('x-token')

  console.log(token) // => abc-123-foo-bar
}

xhr.send()

Set a custom request header for all requests

cy.server({
  onAnyRequest: (route, proxy) => {
    proxy.xhr.setRequestHeader('CUSTOM-HEADER', 'Header value')
  },
})

Change the default filtering

cy.server() comes with an ignore function that by default filters out any requests that are for static assets like .html, .js, .jsx, and .css.

Any request that passes the ignore will be ignored - it will not be logged nor will it be stubbed in any way (even if it matches a specific cy.route()).

The idea is that we never want to interfere with static assets that are fetched via Ajax.

The default filter function in Cypress is:

const ignore = (xhr) => {
  // this function receives the xhr object in question and
  // will ignore if it's a GET that appears to be a static resource
  return (
    xhr.method === 'GET' &&
    /\.(jsx?|coffee|html|less|s?css|svg)(\?.*)?$/.test(xhr.url)
  )
}

You can override this function with your own specific logic:

cy.server({
  ignore: (xhr) => {
    // specify your own function that should return
    // truthy if you want this xhr to be ignored,
    // not logged, and not stubbed.
  },
})

If you would like to change the default option for ALL cy.server() you can change this option permanently.

Turn off the server after you've started it

You can disable all stubbing and its effects and restore it to the default behavior as a test is running. By setting enable to false, this disables stubbing routes and XHR's will no longer show up as (XHR Stub) in the Command Log. However, routing aliases can continue to be used and will continue to match requests, but will not affect responses.

cy.server()
cy.route('POST', '/users', {}).as('createUser')
cy.server({ enable: false })

Notes

State between tests

Server persists until the next test runs

Cypress automatically continues to persist the server and routing configuration even after a test ends. This means you can continue to use your application and still benefit from stubbing or other server configuration.

However between tests, when a new test runs, the previous configuration is restored to a clean state. No configuration leaks between tests.

Outstanding requests are automatically aborted between tests

When a new test runs, any outstanding requests still in flight are automatically aborted. In fact this happens by default whether or not you've even started a cy.server().

cy.visit()

Server can be started before you cy.visit()

Oftentimes your application may make initial requests immediately when it loads (such as authenticating a user). Cypress makes it possible to start your server and define routes before a cy.visit(). Upon the next visit, the server + routes will be instantly applied before your application loads.

You can read more about XHR strategy here.

cy.request()

cy.server() does not effect cy.request()

cy.server() and any configuration passed to cy.server() has no effect on cy.request().

The intention of cy.request() is to be used for checking endpoints on an actual, running server without having to start the front end application.

Rules

Requirements

• cy.server() requires being chained off of cy .

Assertions

• cy.server() cannot have any assertions chained.

Timeouts

• cy.server() cannot time out.

Command Log

• cy.server() does not log in the Command Log

History

See also

• Network Requests
• cy.route()
• cy.wait()