Cypress tem atributo
cy.get('selector')
.should('have.attr', 'aria-checked', 'true')
Tired Tapir
cy.get('selector')
.should('have.attr', 'aria-checked', 'true')
cy.get('input').invoke('attr', 'placeholder').should('contain', 'username')
// have.attr comes from chai-jquery
cy.get('#header a').should('have.attr', 'href', '/users')