Use `cy.should` for the assertions

In Cypress there is cy.should command https://docs.cypress.io/api/commands/should that created especially to make assertions. Currently, we execute all interactions in cy.then context. So technically it doesn't matter how to write tests:

cy.do([
  TextField('User name').fillIn('John Foo'),
  Checkbox('Remember me').is({ checked: true }),
  Button('Submit').click()
])

Or

cy.expect([
  TextField('User name').fillIn('John Foo'),
  Checkbox('Remember me').is({ checked: true }),
  Button('Submit').click()
])

Or

cy.do(TextField('User name').fillIn('John Foo'))
cy.expect(Checkbox('Remember me').is({ checked: true }))
cy.do(Button('Submit').click())

All of them become like this:

cy.then(() => TextField('User name').fillIn('John Foo'))
cy.then(() => Checkbox('Remember me').is({ checked: true }))
cy.then(() => Button('Submit').click())

And also I think, there is no reason to check the runner state and restrict calling actions after assertions. Because users always will have a workaround to do it.

Start with the issue's examples and the Cypress should documentation, then locate the current implementations of cy.do, cy.expect, and their cy.then behavior. The work is done when assertions use cy.should and the runner no longer restricts actions after assertions, with the existing interaction behavior preserved.