New window not opening in cypress

Question

I want to open a new window and create one fake email address in that window. after that I want to close that window.

Here is what I have tried.

it.only('Sign up', function () {
    cy.visit('/')
    cy.xpath('//button[text()=" Sign Up with Email"]').click()
    cy.get('#email').type(email.toLocaleLowerCase())
    cy.fixture("data.json").then(profile => {
        profile.email = email
        cy.writeFile("cypress/fixtures/data.json", profile);

        cy.window().then((win) => {
            cy.stub(win, 'open').as('redirect');
        })
        
        cy.get('.ant-btn').click()
        cy.wait(1000)
        cy.get('@redirect').should('be.calledWith')
    });
});

And here is my test runner image. the window is not called.

And if the window is open, how to use the command in that.