fix: do not set document.referrer while using cy.visit (#18658)

Co-authored-by: David Munechika <david@cypress.io>

packages/driver/cypress/integration/issues/4295_spec.js

@@ -0,0 +1,20 @@
+// https://github.com/cypress-io/cypress/issues/4295
+it('rewrites document.referrer on the AUT to be empty string on visit', () => {
+  cy.visit('http://localhost:3500/fixtures/generic.html')
+
+  cy.window().its('document').its('referrer').should('equal', '')
+})
+
+it('rewrites document.referrer on the AUT to be empty string on visit before user calls onBeforeLoad', () => {
+  cy.visit('http://localhost:3500/fixtures/generic.html', { onBeforeLoad: (contentWindow) => {
+    expect(contentWindow.document.referrer).to.equal('')
+  } })
+})
+
+it('does not rewrite document.referrer if navigation was triggered by click on a link', () => {
+  cy.visit('http://localhost:3500/fixtures/generic.html')
+
+  cy.get('#dimensions').click()
+
+  cy.window().its('document').its('referrer').should('equal', 'http://localhost:3500/fixtures/generic.html')
+})

packages/driver/src/cy/commands/navigation.ts

@@ -789,6 +789,13 @@ export default (Commands, Cypress, cy, state, config) => {
 
           const onBeforeLoad = (contentWindow) => {
             try {
+              // when using the visit the document referrer should be set to an empty string
+              Object.defineProperty(contentWindow.document, 'referrer', {
+                value: '',
+                enumerable: true,
+                configurable: true,
+              })
+
               options.onBeforeLoad?.call(runnable.ctx, contentWindow)
             } catch (err) {
               err.isCallbackError = true