Configuration

cypress.json

The first time you open Cypress Test Runner, it creates the cypress.json configuration file. This JSON file is used to store any configuration values you supply. If you configure your tests to record the results to the Cypress Dashboard the projectId will be written in this file too.

Options

The default behavior of Cypress can be modified by supplying any of the following configuration options. Below is a list of available options and their default values.

Global

Timeouts

Folders / Files

Screenshots

For more options regarding screenshots, view the Cypress.Screenshot API.

Videos

Downloads

Browser

Viewport

Actionability

For more information, see the docs on actionability.

Node version

The Node version is used in Cypress to:

• Build files in the integrationFolder.
• Build files in the supportFile.
• Execute code in the pluginsFile.

Experiments

Configuration might include experimental options currently being tested. See Experiments page.

Overriding Options

Cypress gives you the option to dynamically alter configuration values. This is helpful when running Cypress in multiple environments and on multiple developer machines.

This gives you the option to do things like override the baseUrl or environment variables.

Command Line

When running Cypress from the Command Line you can pass a --config flag.

Examples:

cypress open --config pageLoadTimeout=30000,baseUrl=https://myapp.com

cypress run --config integrationFolder=tests,videoUploadOnPasses=false

cypress run --browser firefox --config viewportWidth=1280,viewportHeight=720

For more complex configuration objects, you may want to consider passing a JSON.stringified object surrounded by single quotes.

cypress open --config '{"watchForFileChanges":false,"testFiles":["**/*.js","**/*.ts"]}'

Runner Specific Overrides

You can override configuration for either the E2E or Component Testing runner using the e2e and component options.

Examples

Component Testing specific viewports in configuration file (cypress.json by default):

{
  "viewportHeight": 600,
  "viewportWidth": 1000,
  "component": {
    "viewportHeight": 500,
    "viewportWidth": 500
  }
}

Testing type specific timeouts in configuration file (cypress.json by default):

{
  "defaultCommandTimeout": 5000,
  "e2e": {
    "defaultCommandTimeout": 10000,
    "slowTestThreshold": 5000
  },
  "component": {
    "slowTestThreshold": 150
  }
}

Plugins

The Cypress plugins file runs in Node environment before the browser running a spec file launches, giving you the most flexibility to set the configuration values. This enables you to do things like:

• Use fs and read off configuration values and dynamically change them.
• Edit the list of browsers found by default by Cypress
• Set config values by reading any custom environment variables

While this may take a bit more work than other options - it yields you the most amount of flexibility and the ability to manage configuration however you'd like.

// cypress/plugins/index.js
module.exports = (on, config) => {
  // modify the config values
  config.defaultCommandTimeout = 10000

  // read an environment variable and
  // pass its value to the specs
  config.env.userName = process.env.TEST_USER || 'Joe'
  // the specs will be able to access the above value
  // by using Cypress.env('userName')

  // IMPORTANT return the updated config object
  return config
}

We've fully documented how to set the configuration values from plugin file here.

Environment Variables

You can also use environment variables to override configuration values. This is especially useful in Continuous Integration or when working locally. This gives you the ability to change configuration options without modifying any code or build scripts.

By default, any environment variable that matches a corresponding configuration key will override the configuration file (cypress.json by default) value.

export CYPRESS_VIEWPORT_WIDTH=800

export CYPRESS_VIEWPORT_HEIGHT=600

We automatically normalize both the key and the value. Cypress will strip off the CYPRESS_, camelcase any keys and automatically convert values into Number or Boolean. Make sure to prefix your environment variables with CYPRESS_ else they will be ignored.

Both options below are valid

export CYPRESS_pageLoadTimeout=100000

export CYPRESS_PAGE_LOAD_TIMEOUT=100000

Test Configuration

We provide two options to override the configuration while your test are running, Cypress.config() and suite-specific or test-specific configuration overrides.

• animationDistanceThreshold
• baseUrl
• blockHosts
• defaultCommandTimeout
• env note: Provided environment variables will be merged with current environment variables.
• execTimeout
• experimentalSessionSupport
• includeShadowDom
• keystrokeDelay
• numTestsKeptInMemory
• pageLoadTimeout
• redirectionLimit
• requestTimeout
• responseTimeout
• retries
• screenshotOnRunFailure
• scrollBehavior
• slowTestThreshold
• viewportHeight
• viewportWidth
• waitForAnimations

Cypress.config()

You can also override configuration values within your test using Cypress.config().

This changes the configuration for the remaining execution of the current spec file. The values will reset to the previous default values after the spec has complete.

Cypress.config('pageLoadTimeout', 100000)

Cypress.config('pageLoadTimeout') // => 100000

Test-specific Configuration

To apply specific Cypress configuration values to a suite or test, pass a configuration object to the test or suite function as the second argument.

The configuration values passed in will only take effect during the suite or test where they are set. The values will then reset to the previous default values after the suite or test is complete.

Syntax

describe(name, config, fn)
context(name, config, fn)
it(name, config, fn)
specify(name, config, fn)

Suite configuration

If you want to target a suite of tests to run or be excluded when run in a specific browser, you can override the browser configuration within the suite configuration. The browser option accepts the same arguments as Cypress.isBrowser().

You can configure the number of times to retries a suite of tests if they fail during cypress run and cypress open separately.

describe(
  'login',
  {
    retries: {
      runMode: 3,
      openMode: 2,
    },
  },
  () => {
    it('should redirect unauthenticated user to sign-in page', () => {
      // ...
    })

    it('allows user to login', () => {
      // ...
    })
  }
)

Single test configuration

If you want to target a test to run or be excluded when run in a specific browser, you can override the browser configuration within the test configuration. The browser option accepts the same arguments as Cypress.isBrowser().

it('Show warning outside Chrome', { browser: '!chrome' }, () => {
  cy.get('.browser-warning').should(
    'contain',
    'For optimal viewing, use Chrome browser'
  )
})

Resolved Configuration

When you open a Cypress project, clicking on the Settings tab will display the resolved configuration to you. This helps you to understand and see where different values came from. Each set value is highlighted to show where the value has been set via the following ways:

• Default value
• The configuration file
• The Cypress environment file
• System environment variables
• Command Line arguments
• Plugins file

Notes

blockHosts

By passing a string or array of strings you can block requests made to one or more hosts.

To see a working example of this please check out our Stubbing Google Analytics Recipe.

To block a host:

• Pass only the host
• Use wildcard * patterns
• Include the port other than 80 and 443
• Do NOT include protocol: http:// or https://

Given the following URLs:

https://www.google-analytics.com/ga.js

http://localhost:1234/some/user.json

This would match the following blocked hosts:

www.google-analytics.com
*.google-analytics.com
*google-analytics.com

localhost:1234

Because localhost:1234 uses a port other than 80 and 443 it must be included.

When Cypress blocks a request made to a matching host, it will automatically send a 503 status code. As a convenience it also sets a x-cypress-matched-blocked-host header so you can see which rule it matched.

modifyObstructiveCode

With this option enabled - Cypress will search through the response streams coming from your server on .html and .js files and replace code that matches patterns commonly found in framebusting.

These script patterns are antiquated and deprecated security techniques to prevent clickjacking and framebusting. They are a relic of the past and are no longer necessary in modern browsers. However many sites and applications still implement them.

These techniques prevent Cypress from working, and they can be safely removed without altering any of your application's behavior.

Cypress modifies these scripts at the network level, and therefore there is a tiny performance cost to search the response streams for these patterns.

You can turn this option off if the application or site you're testing does not implement these security measures. Additionally it's possible that the patterns we search for may accidentally rewrite valid JS code. If that's the case, please disable this option.

firefoxGcInterval

Firefox versions 79 and earlier have a bug where it does not run its internal garbage collection (GC) fast enough, which can lead to consuming all available system memory and crashing.

Cypress prevents Firefox from crashing by forcing Firefox to run its GC cleanup routines between tests.

Running GC is an expensive and blocking routine. It adds significant time to the overall run, and causes Firefox to "freeze" for the duration of GC cleanup. This causes the browser not to respond to any user input.

Cypress runs GC cleanup during cypress run only because we don't expect users to interact with the browser - since this is typically run in CI. We've disabled running GC during cypress open because users typically interact with the browser.

Because GC adds additional time to the overall run, we've added the amount of time this routine has taken to the bottom of the Command Log in the Test Runner.

Configuration

You can control how often GC cleanup runs via the firefoxGcInterval configuration value.

firefoxGcInterval controls whether Cypress forces Firefox to run GC cleanup and how frequently.

By default, we force GC cleanup between every test during cypress run, but do not run any GC cleanup during cypress open using the configuration value below:

{
  "firefoxGcInterval": {
    "runMode": 1,
    "openMode": null
  }
}

You can override how often Cypress runs GC cleanup by setting the firefoxGcInterval config value to:

• null, to disable it for both cypress run and cypress open
• a number, which sets the interval for both cypress run and cypress open
• an object to set different intervals for each mode

Examples

Turn off GC cleanup all modes

{
  "firefoxGcInterval": null
}

Run GC cleanup before every other test during cypress run and cypress open

{
  "firefoxGcInterval": 2
}

Run GC cleanup before every 3rd test during cypress run and disable running GC cleanup during cypress open.

{
  "firefoxGcInterval": {
    "runMode": 3,
    "openMode": null
  }
}

isInteractive

You can open Cypress in the interactive mode via the cypress open command, and in run mode via the cypress run command. To detect the mode from your test code you can query the isInteractive property on Cypress.config.

if (Cypress.config('isInteractive')) {
  // interactive "cypress open" mode!
} else {
  // "cypress run" mode
}

Intelligent Code Completion

IntelliSense is available for Cypress while editing your configuration file. Learn how to set up Intelligent Code Completion.

Common problems

baseUrl is not set

Make sure you do not accidentally place the baseUrl or another top-level config variable into the env block. The following configuration is incorrect and WILL NOT WORK:

// ⛔️ DOES NOT WORK
{
  "env": {
    "baseUrl": "http://localhost:3030",
    "FOO": "bar"
  }
}

Solution: place the baseUrl property at the top level, outside the env object.

// ✅ THE CORRECT WAY
{
  "baseUrl": "http://localhost:3030",
  "env": {
    "FOO": "bar"
  }
}

You can also find a few tips on setting the baseUrl in this short video.

Test files not found when using spec parameter

When using the --spec <path or mask> argument, make it relative to the project's folder. If the specs are still missing, run Cypress with DEBUG logs with the following setting to see how the Test Runner is looking for spec files:

DEBUG=cypress:cli,cypress:server:specs

History

See also

• Cypress.config() and Cypress.env()
• Environment variables
• Environment Variables recipe
• Extending the Cypress Config File blog post and @bahmutov/cypress-extends package.
• Blog post Keep passwords secret in E2E tests