I found many different approaches to stubbing the window.open call, but none of them worked out of the box.
In my use case there's a button that launches a click event. The click event then opens a new tab with a dynamic url that I wanted to grab.
The answer is a mix of a great post: https://glebbahmutov.com/blog/stub-window-open/ and Cypress: Stub open window.
This example should work with Cypress 10.x
// Listen to window:before:load events, modify the window object before the app code runs between page transitions
// Create a stub with the alias windowOpen, choose whatever you like
// Grab the url parameter that the page was trying to open and visit the page
cy.on('window:before:load', (win) => {
cy.stub(win, 'open').as('windowOpen').callsFake(url => {
cy.visit(url);
})
})
// Start by visiting the page you'll run your tests in. I'm using the baseUrl here.
cy.visit("/");
// Do whatever tests need to be done before the action the opens a new tab
// Now the element that fires a click event which then uses window.open to open a new tab
cy.contains("Ok").click();
// The stub should now have picked the url and called cy.visit(url)
// The page that would normally open in a new tab, should be visible in the same page
// Now the next commands are intended to run in the new page and should be able to complete
cy.get(".whateverselectoryouwant")
.should('have.text', 'whateveryourtextisonthenewpage')