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Experiments

If you'd like to try out what we're working on in Cypress, you can enable alpha features for your project by turning on the experimental features you'd like to try.

caution

⚠️ The experimental features might change or ultimately be removed without making it into the core product. Our primary goal for experiments is to collect real-world feedback during their development.

Configuration

You can pass the Cypress configuration options below to enable or disable experiments. See our Configuration Guide on how to pass configuration to Cypress.

OptionDefaultDescription
experimentalFetchPolyfillfalseAutomatically replaces window.fetch with a polyfill that Cypress can spy on and stub. Note: experimentalFetchPolyfill has been deprecated in Cypress 6.0.0 and will be removed in a future release. Consider using cy.intercept() to intercept fetch requests instead.
experimentalInteractiveRunEventsfalseAllows listening to the before:run, after:run, before:spec, and after:spec events in the setupNodeEvents function during interactive mode.
experimentalMemoryManagementfalseEnables support for improved memory management within Chromium-based browsers.
experimentalModifyObstructiveThirdPartyCodefalseWhether Cypress will search for and replace obstructive code in third party .js or .html files. NOTE: Setting this flag removes Subresource Integrity (SRI).
experimentalSourceRewritingfalseEnables AST-based JS/HTML rewriting. This may fix issues caused by the existing regex-based JS/HTML replacement algorithm. See #5273 for details.
experimentalWebKitSupportfalseEnable experimental support for running tests in WebKit. When set, installs of playwright-webkit will be detected and available in Cypress. See Launching Browsers for more information.

Testing Type-Specific Experiments

You can provide configuration options for either E2E or Component Testing by creating e2e and component objects inside your Cypress configuration.

End-to-End Testing

These experiments are available to be specified inside the e2e configuration object:

OptionDefaultDescription
experimentalStudiofalseGenerate and save commands directly to your test suite by interacting with your app as an end user would.
experimentalRunAllSpecsfalseEnables the "Run All Specs" UI feature, allowing the execution of multiple specs sequentially.
experimentalOriginDependenciesfalseEnables support for require/import within cy.origin.
experimentalSkipDomainInjectionnullRemoves injecting document.domain into text/html pages for any sites that match the provided patterns.

Experimental Skip Domain Injection

Under the hood, Cypress injects document.domain into your test application to lessen the burden of navigation. This is well described in our Cross Origin Testing guide. However, some sites have compatibility issues with this feature.

The experimentalSkipDomainInjection option disables injecting document.domain inside Cypress. When enabled, all cross-origin/subdomain navigation must use cy.origin(), which may make tests a bit more verbose. We only recommend including your site pattern if you are having issues running Cypress out of the box and suspect setting document.domain is interfering with your site's ability to render properly.

Before enabling, verify your application is not implementing frame busting techniques, which you can mitigate with the modifyObstructiveCode and experimentalModifyObstructiveThirdPartyCode flags.

At this point in time, we are aware of the following sites that require the experimentalSkipDomainInjection option to be set to be tested properly:

  • Google
  • Salesforce

This flag can be enabled by passing an array of origin URLs or minimatch glob patterns:

const { defineConfig } = require('cypress')

module.exports = defineConfig({
e2e: {
experimentalSkipDomainInjection: [
'*.salesforce.com',
'*.force.com',
'*.google.com',
],
},
})

If using other Salesforce domains, such as enhanced domains, you will need to add the correct matching glob pattern.

Component Testing

These experiments are available to be specified inside the component configuration object:

OptionDefaultDescription
experimentalSingleTabRunModefalseRun all specs in a single tab, instead of creating a new tab per spec. This can improve run mode performance, but can impact spec isolation and reliability on large test suites.

History

VersionChanges
12.4.0Added experimentalSkipDomainInjection and experimentalMemoryManagement.
12.0.0Removed experimentalSessionAndOrigin and made it the default behavior. Added experimentalOriginDependencies.
11.2.0Added experimentalRunAllSpecs.
10.8.0Added experimentalWebKitSupport.
10.6.0Added support for experimentalSingleTabRunMode.
10.4.0Added support for experimentalModifyObstructiveThirdPartyCode.
9.6.0Added support for experimentalSessionAndOrigin and removed experimentalSessionSupport.
8.2.0Added support for experimentalSessionSupport.
7.1.0Added support for experimentalInteractiveRunEvents.
7.0.0Removed experimentalComponentTesting and made it the default behavior.
6.7.0Removed experimentalRunEvents and made it the default behavior.
6.3.0Added support for experimentalStudio.
6.2.0Added support for experimentalRunEvents.
6.0.0Removed experimentalNetworkStubbing and made it the default behavior when using cy.intercept().
6.0.0Deprecated experimentalFetchPolyfill.
5.2.0Removed experimentalShadowDomSupport and made it the default behavior.
5.1.0Added support for experimentalNetworkStubbing.
5.0.0Removed experimentalGetCookiesSameSite and made it the default behavior.
4.9.0Added support for experimentalFetchPolyfill.
4.8.0Added support for experimentalShadowDomSupport.
4.6.0Added support for experimentalSourceRewriting.
4.5.0Added support for experimentalComponentTesting.
4.3.0Added support for experimentalGetCookiesSameSite.