Example anchor ping stub in Cypress

ping-spec.js

```js
/// <reference types="Cypress" />
describe('intercept', () => {
  it('stubs anchor ping', () => {
    cy.visit('/')
    cy.intercept({
      method: 'POST',
      pathname: '/track'
    }, {}).as('ping')
    cy.get('a[ping]').click()
    cy.location('pathname').should('equal', 'page2.html')
    cy.wait('@ping').its('request.headers').should('deep.include', {
      'ping-from': `${Cypress.config('baseUrl')}/`,
      'ping-to': `${Cypress.config('baseUrl')}/page2.html`,
    })
  })
})
```