Example using window.open to "pop" application and test it from Cypress test runner. This allows top === self and bypasses what many windows do to frame-bust, see cypress/issues/886.
Read Cypress using child window.
See cypress/integration/spec.js, but basically there is a custom command cy.openWindow that uses window.open to create a child window linked back synchronously to the opener window. This still lets Cypress work.
To execute (note, requires Chrome browser):
npm run devTime traveling debugger should still work - and it shows the snapshots in the iframe, not in the child window
